IC-NRLF 


MODEL  AEROPLANES 

AND  THEIR  MOTORS 


Waid  Carl's  model  in  flight 
Courtesy  Edward  P.  Warner,  Concord  Model  Club 


MODEL  AEROPLANES 

AND  THEIR  MOTORS 

A  Practical  Book  for  Beginners 

BY 

GEORGE  A.  CAVANAGH 

MODEL  EDITOR  "AERIAL  AGE" 


DRAWINGS  BY 

HARRY  G.  SCHULTZ 

PRESIDENT  THB  AERO-SCIENCB  CLUB  OF  AMERICA 


WITH  AN  INTRODUCTION   BY 

HENRY  WOODHOUSE 

Managing  Edltoi  "Flying" 
Governor  of  ihe  Aero  CluH  of  America 


NEW  YORK 

MOFFAT,  YARD  &  COMPANY 
1916 


e 


COPYRIGHT,  1916,  Bv 

MOFFATT,  YARD  AND  COMPANY 

NEW  YORK 


All  Hfhu  rturvid 


TO 
M.  T.  H. 


INTRODUCTION 

HISTORY  tells  us — what  some  of  us  luckier 
ones  heard  the  Wright  Brothers  themselves 
tell — that  the  Wrights'  active  work  in  aero- 
nautics was  a  result  of  the  interest  aroused  by 
a  toy  helicopter  presented  to  them  by  the  Rev- 
erend Bishop  Milton  Wright,  their  father. 

Tremendous  developments  have  taken  place 
in  aeronautics  and  aircraft  are  fast  developing 
in  size,  speed,  and  range  of  action.  They 
have  revolutionized  warfare,  and  seem  to  be 
destined  to  become  a  most  important  factor  in 
the  reconstruction  that  will  follow  the  war. 

The  greater  the  development  the  truer  the 
fact  that  model  aeroplanes  may  be  instru- 
mental in  bringing  to  aeronautics  men  who 
may  make  valuable  contributions  to  aeronaut- 
ics. As  a  matter  of  fact,  there  are  already 
in  active  life,  contributing  their  share  to  the 
development  of  aeronautics,  young  men  who 
only  a  few  years  ago  competed  for  prizes 


INTRODUCTION 

which  the  writer  offered  for  model  competi- 
tion. 

The  young  men  who  are  now  flying  models 
will  live  in  the  new  age — and  they  have  much 
to  give  and  much  to  receive  from  it 

Through  the  tremendous  strides  forward  of 
aeronautics  there  are  wonderful  possibilities 
for  the  employment  of  ingenuity,  genius  and 
skill,  and  business  opportunities,  as  great  as 
have  ever  been  created  by  progress  in  impor- 
tant lines  of  human  endeavor.  Problems  of 
engineering  as  huge  as  were  solved  by  master 
builders;  juridical  and  legal  questions  to  be 
decided  as  stupendously  difficult  as  any  Glad- 
stone would  wish  them;  possibilities  for  the 
development  of  international  relations  greater 
than  were  ever  conceived;  problems  of  trans- 
portation to  be  solved  by  the  application  of 
aircraft,  as  wonderful  as  any  economist  could 
wish;  opportunities  to  gain  distinction  splen- 
did enough  to  satisfy  the  most  ambitious 
person. 

HENRY  WOODHOUSE. 

New  York,  June  5th,  1916. 


LIST  OF  CONTENTS 

PAGE 

INTRODUCTION      .     .     * ix 

HISTORY  OF  MODEL  AVIATION i 

CONSTRUCTION     ...... 8 

Propellers— Wings— Frame —  Assembling—  Launching 
Chassis — Pontoons — Launching  an  R.  O.  G.  or  Model 
Hydroaeroplane. 

WORLD   RECORD   MODELS 52 

Lauder  Distance  and  Duration  Model— Hittle  Tractor 
Hydro — La  Tour  Flying  Boat — Cook  No.  42  Model — 
Alson  H.  Wheeler  Twin  Pusher  Biplane— Rudy  Funk 
Duration  Model. 

COMPRESSED  AIR  MOTOR 83 

A  Simple  Compressed  Air  Motor — Wise  Compressed 
Air  Motor — Schober-Funk  Three  Cylinder  Motor — 
The  Schober  Four  Cylinder  Opposed  Motor, 

COMPRESSED  AIR  DRIVEN  MODELS   ......      .     .    92 

The  McMahon  Compressed  Air  Driven  Monoplane — 
The  McMahon  Compressed  Air  Driven  Biplane. 

GASOLINE  MOTORS— JOPSON— MIDGET  A£RO  GASOLINE  MOTOR  112 

STEAM  POWER  PLANTS      , 114 

H.  H.  Groves  Steam  Power  Plants— G.  Harris's 
Steam  Engine — Professor  Langley's  Steam  Engine — 
French  Experiments  with  Steam  Power  Plants, 

WORLD'S  MODEL  FLYING  RECORDS 119 

DICTIONARY  OF  AERONAUTICAL  TERMS  .  .,        .    .  122 


LIST  OF  ILLUSTRATIONS 

PAGE 

Model  Aeroplane  in  Flight Frontispiece 

First  Model  Aeroplane  Exhibition  ......  Opp.  4 

Propellers  (Diagram  i) ,...  9 

How  to  cut  propellers  (Diagram  2) u 

Designs  for  propellers  (Diagram  3) .  .  14 

Designs  for  propellers  (Diagram  4) 17 

Wing  construction  (Diagram  5) 20 

Members  of  the  Aero  Science  Club Opp.  22 

Members  of  the  Milwaukee,"  and  Illinois  Model  Aero 

Clubs Opp.  22 

Frame  construction  (Diagram  6) .  .25 

Model  Assembly  (Diagram  7) 30 

C  W.  Meyer  and  Wm.  Hodgins  exhibiting  early  type 

models Opp.  32 

Henry  Criscouli  with  five  foot  model Opp.  32 

Schultz  hydroaeroplane Opp.  32 

Rubber  winder  (Diagram  8) 35 

Chassis  construction  (Diagram  9)  ......  ...  38 

Pontoon  construction  (Diagram  10) 43 

Obst  flying  boat Opp.  44 

McLaughlin  twin  tractor  hydroaeroplane  ....  Opp.  44 

Louis  Bamberger  hydro  about  to  leave  water  .  .  Opp.  44 
E.  B.  Hiring  and  Kennith  Sedgwick  Milwaukee  Club. 

How  to  launch  R.  O.  G.  model Opp.  48 

Waid  Carl,  Concord  Model  Club.  Launching  R.  O.  G. 

model Opp.  48 


LIST  OF  ILLUSTRATIONS 

PAGE 

Wallace  A.  Lauder  model  (Diagram  n)  .     ......    54 

Lauder  distance  and  duration  model Opp.    56 

Lauder  R.  0.  G.  model  . Opp.    56 

Lindsay  Hittle  world  record  hydroaeroplane  (Diagram  12)    61 

La  Tour  Flying  Boat  (Diagram  13) 66 

Ellis  Cook  R.  O.  G  model  (Diagram  14) 73 

Funk  duration  model  (Diagram  15) 78 

Rudy  Funk  speed  model Opp.    80 

McMahon  and  Schober  compressed  air  driven  models  Opp.    80 
Alson  H.  Wheeler  twin  pusher  biplane  ....    Opp.    82 

C.  V.  Obst  tractor  .     , Opp.    82 

Simple  compressed  air  motor  (Diagram  16) 85 

Schober  compressed  air  driven  monoplane  .     .     .    Opp.    88 
Schober  compressed  air  driven  biplane     ....    Opp.    88 
John    McMahon    and    compressed    air    driven    mono- 
plane  Opp.    94 

Frank  Schober  preparing  model  for  flight  .     .     .    Opp.    94 
John  McMahon  pusher  biplane  (Diagram  17)   ...     .    98 

Wise  compressed  air  motor Opp.  100 

Schober-Funk  five-cylinder  rotary  motor  ....    Opp.  100 

Schober  four  cylinder  engine  (Diagram  18) 103 

Jopson  gasoline  motor  . Opp.  104 

Sectional  view  of  Jopson  motor   (Diagram  19)    ...  108 
Power  curve  of  Jopson  motor  (Diagram  20)   .     .     .     .in 

Midget   gasoline   motor Opp.  112 

English  steam  power  plant ,     .    Opp.  116 

V.  E.  Johnson  steam  driven  hydroaeroplane  .     .     .    Opp.  116 

English  compressed  air  driven  biplane Opp.  118 

Tractor  hydroaeroplane  fitted  with  steam  power  plant  . . 

....    Opp.  118 

English  compressed  air  motor  fitted  with  simple  speed- 
ometer   ;  ........   Opp.  118 


MODEL  AEROPLANES 

HISTORY  OF  MODEL  AVIATION 

MODEL  aeroplaning,  as  a  sport,  was  first  in- 
troduced in  America  during  the.  year  of  1907. 
It  was  then  that  the  first  model  aeroplane  club 
in  America  was  formed  by  Miss  E.  L.  Todd, 
with  the  assistance  of  Mr.  Edward  Durant, 
now  Director  of  the  Aero  Science  Club  of 
America.  Prior  to  this  the  model  aeroplane 
was  considered  an  instrument  of  experimenta- 
tion or,  when  built  to  resemble  a  full  sized 
machine,  was  used  for  exhibition  purposes. 
Noted  scientists,  men  such  as  Maxim,  Langley, 
Eiffel  and  others,  depended  largely  on  models 
to  bring  about  the  desired  results  during  their 
experiments.  Before  the  Wright  Brothers 
brought  forth  and  launched  the  first  heavier 
than  air  machine  their  experiments,  to  a  great 


2  MODEL  AEROPLANES 

extent,  were  confined  to  model  aeroplanes. 
There  is  little  doubt  but  that  a  large  majority 
of  aviators  engaged  in  flying  machines  in  dif- 
ferent parts  of  the  world  were  at  one  time  in 
their  career  interested  in  the  construction  and 
flying  of  model  aircraft,  and  from  which  no 
doubt  they  obtained  their  initial  knowledge  of 
the  aeroplane,  in  so  far  as  the  same  principles 
and  laws  apply  to  any  aeroplane,  regardless  of 
its  size. 

The  first  model  aeroplane  club  went  under 
the  name  of  the  New  York  Model  Aero  Club 
and  during  its  existence  a  great  many  of  its 
contests  were  carried  on  in  armories.  The 
reason  for  this  was  because  of  the  fact  that  the 
greater  number  of  the  models  prevalent  at  that 
time  were  built  along  the  lines  of  full  sized 
machines,  and  their  manner  of  construction 
was  such  as  to  interfere  with  the  flying  ef- 
ficiency of  the  model.  Streamline  construction 
was  something  unknown  to  model  constructors 
in  those  days  and,  in  consequence,  crudely  con- 
structed and  heavy  models  were  very  often  evi- 


HISTORY  3 

denced,  and,  as  a  result,  flights  of  over  one 
hundred  feet  were  very  seldom  made.  At  about 
the  same  time  model  enthusiasts  in  both  Eng- 
land and  France  were  actively  engaged  in  con- 
structing and  flying  models,  but  the  type  of 
model  used  was  of  a  different  design  from  those 
flown  by  the  American  modelists  and  as  a  re- 
sult of  this  innovation  many  of  the  early  rec- 
ords were  held  abroad.  The  type  of  model 
flown  by  the  English  modelists  resembled  in  ap- 
pearance the  letter  "A,"  hence  the  term  "A" 
type. 

It  was  not  long  after  the  introduction  of  this 
type  of  model  in  America  that  model  aero- 
planing  as  a  sport  began  to  assume  an  aspect  of 
great  interest.  Models  were  constructed  along 
simpler  lines  and  with  a  greater  tendency 
toward  doing  away  with  all  unnecessary  parts, 
thus  increasing  the  flying  qualities  of  the 
models.  Flights  of  greater  distance  and  dura- 
tion were  the  objects  sought  and,  in  their  efforts 
to  achieve  them  new  records  were  made  at  most 
every  contest,  until  flights  of  from  500  to  1000 


4  MODEL  AEROPLANES 

feet  were  common  occurrences.  By  the  use  of 
the  A  type  model  and  the  single  stick  model 
which  made  its  appearance  shortly  after  the  A 
type  model,  American  modelists  succeeded  in 
breaking  most  of  the  world  records  for  this 
type  of  model  which  is  now  termed  by  English 
modelists  "flying  sticks." 

One  by  one  model  aeroplane  clubs  were 
formed  in  different  parts  of  the  country  until 
to-day  there  are  in  existence  about  twenty-five 
clubs  and  all  with  memberships  of  from  two  to 
eight  times  that  ojf  the  first  model  aero  club. 
The  work  which  was  started  by  the  New  York 
Model  Aero  Club  is  now  being  carried  on  by  the 
Aero  Science  Club  of  America  and  its  affiliated 
clubs.  The  interest  in  model  flying  grew  to 
such  an  extent  that  during  the  year  of  1915  the 
Aero  Club  of  America  decided  to  hold  the  First 
National  Model  Aeroplane  Competition  for  the 
purpose  of  offering  to  the  young  men  of  Amer- 
ica an  opportunity  of  becoming  acquainted 
with  this  new  sport  and  its  advantages.  The 
results  of  this  competition  were  beyond  expec- 


HISTORY  5 

tation.  Models  were  made  capable  of  flying 
distances  and  with  durations  that,  to  the 
early  flyers,  seemed  impossible.  In  the  hand 
launched  contests  models  were  flown  for  dis- 
tances ranging  from  2000  to  2500  feet,  the  win- 
ning flight  being  3537  feet,  and  it  might  also 
be  said  that  the  contestant  who  flew  this  model, 
with  a  model  of  the  same  design  established  a 
duration  record  of  195  seconds.  As  this  goes 
to  press,  information  is  received  that  the 
World's  Record  for  distance  for  hand  launched 
models  has  been  broken  by  Thomas  Hall,  of 
Chicago,  111.,  an  Illinois  Model  Aero  Club  mem- 
ber, with  a  flight  of  5337  feet.  Another  in- 
teresting result  of  the  competition  was  the  es- 
tablishing of  a  world  hydroaeroplane  record  by 
a  member  of  the  Illinois  Model  Aero  Club  with 
a  model  of  the  tractor  type,  a  f our-bladed  pro- 
peller being  used  in  connection  with  the  model. 
The  flying  boat  which  is  a  late  advent  to  the 
field  of  model  flying  also  proved  a  record 
breaker  in  this  competition,  having  remained  in 
the  air  after  rising  from  the  surface  of  the 


6  MODEL  AEROPLANES 

water,  for  a  duration  of  43  seconds.  This 
model  was  flown  by  a  member  of  the  Pacific 
Northwest  Model  Aero  Club  of  Seattle,  Wash- 
ington. The  establishing  of  these  records 
clearly  indicates  the  advantage  of  scientific  de- 
signing and  construction  and  careful  handling. 
So  satisfactory  have  been  the  results  of  the 
First  National  Model  Aeroplane  Competition 
that  the  Aero  Club  of  America  has  made  ar- 
rangements for  holding  the  Second  National 
Model  Aeroplane  Competition  during  the 
year  1916.  But  in  the  announcement  of  the 
Second  National  Competition  the  Aero  Club  of 
America  has  made  provision  for  the  holding  of 
contests  for  mechanically  driven  models,  in 
view  of  the  interest  which  is  being  shown  by 
model  flyers  in  the  construction  of  models 
more  closely  resembling  large  machines  to  be 
driven  by  compressed  air,  steam  and  gasoline 
power  plants.  This  is  the  outcome  of  a  desire 
on  the  part  of  model  constructors  to  substitute 
for  what  is  now  commonly  known  as  the  "flying 
stick,"  models  more  closely  resembling  large 


HISTORY  7 

machines,  which  models  can  be  more  satisfac- 
torily flown  by  the  use  of  compressed  air,  steam 
or  gasoline  power  plants.  As  in  the  early  days, 
the  best  flights  made  by  models  using  com- 
pressed air  and  steam  have  been  made  by  Eng- 
lish flyers,  the  duration  of  the  flights  ranging 
anywhere  from  25  to  50  seconds. 

Whether  or  not  the  American  flyers  will  re- 
peat history  and  achieve  greater  results  with 
this  type  of  model  motive  power  is  something 
that  can  only  be  determined  in  the  future.  But 
in  any  event  the  scientific  mechanically  driven 
model  will,  without  doubt,  assume  an  important 
position  in  the  field  of  model  aviation. 


CONSTRUCTION 

PROPELLERS 

PROPELLERS  may  be  cut  from  various  kinds 
of  wood,  but  the  most  suitable,  from  every 
standpoint,  is  white  pine.  The  advantage  of 
using  this  wood  lies  in  the  fact  that  the  propel- 
lers may  be  cut  more  rapidly  and  when  cut  are 
lighter  than  those  made  from  most  other  kinds 
of  wood.  When  coated  with  the  proper  kind 
of  varnish  they  are  sufficiently  strong  for  or- 
dinary flying.  Wood  selected  for  propellers 
should  be  free  from  knots,  holes  and  other  im- 
perfections and  it  is  very  desirable  that  it 
should  be  of  perfectly  straight  grain. 

A  piece  of  such  clear  white  pine  8"  long,  i" 
wide  and  £4"  thick  should  be  selected  and  on 
one  side  marked  TOP.  A  tracing  of  the  pro- 
peller similar  in  design  to  Figure  I,  should  be 
laid  on  this  piece  of  wood  and  an  imprint  of  the 

propeller  design  drawn  on  the  TOP  side.    To 

8 


CONSTRUCTION 


Diagram  I 


10  MODEL  AEROPLANES 

find  the  center  of  the  block  two  lines  should  be 
drawn  from  the  opposite  corners,  their  point  of 
meeting  being  approximately  in  the  center — 
near  enough  for  all  practical  purposes  to  insure 
greater  accuracy.  Similar  lines  should  be 
drawn  from  the  corners  on  the  BOTTOM  side  of 
the  block  of  wood.  A  hole  3-32  of  an  inch  in 
diameter  should  be  bored  through  the  center 
thus  obtained,  through  which  the  propeller 
shaft  will  be  inserted  when  the  propeller  is 
finished.  The  two  sections  of  the  propeller 
blades  drawn  in  diagrammatical  form  on  the 
TOP  of  the  block,  should  be  marked  respec- 
tively BLADE  i  and  BLADE  2,  as  shown  in 
diagram  I.  The  block  is  then  ready  for  the 
commencement  of  the  actual  cutting.  In  cut- 
ting out  the  propeller,  BLADE  i  should  be  held  in 
the  left  hand  and  the  knife  in  the  other,  with 
the  blade  of  the  knife  on  the  straight  edge  of 
BLADE  i.  The  cutting  should  be  carried  out 
very  carefully  with  attention  constantly  paid  to 
Fig.  2-,  and  should  be  stopped  when  the  line 
shown  in  Fig.  2  has  been  reached.  The  semi- 


CONSTRUCTION 


II 


Diagram  2 


12  MODEL  AEROPLANES 

blade  should  then  be  sandpapered  until  a  small 
curve  is  obtained  by  which  the  propeller  will  be 
enabled  to  grip  the  air. 

To  cut  BLADE  2,  BLADE  I  should  be  held  in 
the  left  hand  and  BLADE  2  cut  until  the  line 
shown  in  Fig.  3  is  reached,  after  which  the 
sandpapering  process  is  carried  out  in  the  same 
manner  as  in  the  case  of  BLADE  i.  During  all 
of  the  foregoing  operations  it  must  be  clearly 
borne  in  mind  that  the  TOP  of  the  blank  pro- 
peller must  always  face  upward,  and  the  cutting 
should  always  be  done  on  the  STRAIGHT  lines. 
Should  the  straight  edge  be  cut  on  one  edge  of 
the  blank  propeller  and  the  curved  edge  on  the 
other,  it  would  result  in  the  blades  of  the 
finished  propeller  having  a  tendency  to  push  in 
opposite  directions  and  in  consequence  no  pro- 
pulsion of  the  model  would  be  possible. 

Attention  should  next  be  turned  to  the  back 
of  the  propeller  blank  on  which  the  manner  of 
cutting  is  exactly  like  that  suggested  for  the  top 
side,  with  the  exception  that  instead  of  cutting 
along  the  STRAIGHT  lines,  the  cutting  is  done 


CONSTRUCTION  >  13 

along  the  CURVED  lines.  In  this  part  of  the 
work  great  care  is  to  be  exercised  for  by  the 
time  the  necessary  cutting  has  been  done  on  the 
back  of  the  propeller  the  entire  structure  is  very 
fragile  and  one  excessive  stroke  of  the  knife 
may  result  in  destroying  the  entire  propeller 
blade.  By  constantly  holding  the  wood  to  the 
light  it  is  possible  to  determine  with  a  reason- 
able degree  of  accuracy  the  evenness  of  thick- 
ness. To  complete  the  BOTTOM  side  of  the  pro- 
peller the  blade  should  be  sandpapered  as  was 
the  top. 

The  method  of  cutting  the  second  propeller 
is  exactly  that  used  in  cutting  the  first  propeller, 
only  that  the  diagram  shown  in  Fig.  4  should  be 
used.  This  will  result  in  two  propellers  being 
made  that  will  revolve  in  opposite  directions  in 
order  to  produce  even  and  balanced  propulsion. 
If  both  propellers  revolved  in  the  same  direc- 
tion the  effect  would  be  to  overturn  the  model. 

In  diagram  I  the  propellers  are  shown  with 
the  straight  edge  as  the  entering  or  cutting 
edge  of  the  blade.  Some  of  the  model  builders 


MODEL  AEROPLANES 


Diagram  3 


CONSTRUCTION  15 

prefer  the  curved  edge  as  the  cutting  edge 
(diagram  2).  It  is  significant  that  Mr.  Frank 
Schober,  a  well  known  model  constructor, 
tested  both  designs  on  his  compressed  air 
driven  model,  and  while  both  propellers  were 
the  same  in  weight,  diameter  and  pitch,  the 
one  having  the  straight  edge  as  the  cutting 
edge  was  found  one-third  more  efficient. 

When  the  propellers  have  been  given  a  light 
coat  of  shellac  they  should  be  laid  aside  until 
the  assembling  of  the  complete  model. 

By  following  the  foregoing  instructions  a 
simple  and  effective  set  of  propellers  will  be 
produced.  But  in  order  to  vary  the  experi- 
mental practice  of  the  constructor  various  other 
diagrams,  Nos.  3  and  4,  illustrating  suitable 
designs,  are  provided  and  can  be  made  by  ap- 
plying the  above  general  theory  and  using  the 
diagrams  herewith. 

WINGS 

One  of  the  most  important  considerations  in 
the  construction  of  a  model  is  the  making  of  the 


16  MODEL  AEROPLANES 

wings.  To  obtain  the  greatest  efficiency  the 
wings  must  be  carefully  designed,  with  due  at- 
tention to  whether  the  model  is  being  con- 
structed for  speed,  duration  or  climbing  ability. 
Attention  should  be  given  to  streamline  con- 
struction ;  that  is,  the  parts  of  the  wing  should 
be  so  assembled  that  the  completed  wing  would 
offer  the  least  possible  resistance  to  the  air,  if 
the  best  results  are  to  be  obtained. 

For  the  main  wing  three  strips  of  spruce, 
each  30"  in  length,  two  of  them  being  3-16"  x 
J4"  and  the  third  3-16"  x  1-16"  are  required. 
To  make  them  thoroughly  streamline  all  edges 
should  be  carefully  rounded  off  and  all  surfaces 
should  be  smooth.  A  strip  of  bamboo  at  least 
20"  long,  y2"  wide,  J^"  thick,  should  be  cut 
into  pieces,  each  piece  to  be  5  in.  long.  To 
secure  the  necessary  curve,  %"  depth,  the 
pieces  of  bamboo  should  be  held  in  steam  and 
slowly  bent  in  a  manner  closely  resembling  the 
skids  of  an  ordinary  bob-sled.  When  the 
curvature  has  been  obtained,  care  should  be 
exercised  in  cutting  each  piece  into  four  longi- 


CONSTRUCTION 


Diagram  4 


18  MODEL  AEROPLANES 

tudinal  strips,  from  which  twelve  should  be 
selected  to  be  used  as  ribs,  each  to  be  J^j" 
wide.  The  bending  of  the  bamboo  preliminary 
to  making  the  ribs  is  done  in  order  to  secure  uni- 
formity of  curvature. 

When  this  has  been  done  the  ribs  are  ready 
for  fastening  to  the  sticks — entering  and  trail- 
ing edges — and  each  must  be  attached  an  equal 
distance  apart.  In  order  that  the  ribs  may  be 
evenly  spaced  it  is  necessary  to  put  a  mark 
every  3"  on  the  larger  stick  or  entering  edge 
of  the  wing,  and  also  on  the  flat  stick  or  trailing 
edge.  The  main  beam  which  is  of  the  same 
dimensions  as  the  entering  edge  is  afterwards 
fastened  across  the  center  of  the  wing,  and  does 
not  necessarily  need  to  be  thus  marked,  as  it  is 
fastened  to  the  ribs  after  the  ribs  have  been 
attached  to  the  entering  and  trailing  edges  of 
the  wing  frame.  By  holding  the  ribs  one  at  a 
time  so  that  the  curved  edge  rests  upon  the  en- 
tering edge  where  the  mark  indicates,  as  shown 
in  diagram  5,  they  should  be  fastened  thereon 
by  means  of  thread  and  glue.  The  rear  end  of 


CONSTRUCTION  19 

the  rib  must  be  fastened  to  the  trailing  edge 
where  the  mark  indicates,  also  by  thread  and 
glue. 

After  all  ribs  have  been  thus  securely  fast- 
ened to  both  edges  of  the  frame  the  third  stick, 
or  main  beam,  should  be  attached  to  the  frame 
on  the  underside,  the  fastening  being  made  at 
the  highest  point  of  the  curve  of  each  rib.  This 
main  beam  prevents  the  wing  covering  from 
drawing  in  the  end  ribs  and  adds  very  materi- 
ally to  the  strength  of  the  entire  wing  struc- 
ture. To  cover  the  wings  fiber  paper  may  be 
used  and  is  a  suitable  material,  but  the  best  re- 
sults, from  a  standpoint  of  flying  efficiency  and 
long  service,  are  obtained  by  the  use  of  China 
silk. 

The  frame  of  the  forward  wing  or  elevator 
is  made  in  the  same  manner  as  is  the  main  wing, 
but  it  is  only  12"  in  span  by  4"  in  chord,  and 
is  constructed  without  the  use  of  a  main 
beam.  This  wing  has  only  five  ribs  which  are 
made  in  the  same  manner  as  those  for  the  rear 
wing,  and  each  is  placed  a  distance  of  3"  apart. 


20 


MODEL  AEROPLANES 


I 


Diagram  5 


CONSTRUCTION  21 

A  piece  of  silk  measuring  2"  longer  and  2" 
wider  than  each  of  the  wing  frames  should 
be  used  in  covering  the  wings,  and  this  can  be 
held  in  position  by  the  use  of  pins  prior  to  the 
actual  sewing.  The  extra  inch  of  silk  on  all 
sides  of  the  frame  is  placed  around  the  under 
side  of  the  frame — in  order  that  it  can  be  made 
thoroughly  taut  when  the  silk  has  been  sewn 
close  to  the  edges  of  the  frame.  After  the  silk 
has  been  sewn  close  to  the  edges  the  pins  may  be 
removed  and  the  surplus  silk  that  hangs  from 
the  under  side  of  the  frame  may  be  cut  off.  To 
make  this  silk  airproof  it  should  be  coated  with 
a  thin  coat  of  shellac  or  varnish  and  the  wings 
should  be  thoroughly  dry  before  being  used. 
This  coating,  in  addition  to  airproofing,  will  as- 
sist in  making  the  covering  perfectly  taut,  and 
also  in  making  the  wing  ready  for  service  when 
the  entire  model  is  ready  to  be  assembled. 

FRAME 

As  all  other  parts  of  the  model  are  attached 
to  the  frame  in  addition  to  its  having  to  stand 


22  MODEL  AEROPLANES 

the  strain  of  the  tightly  wound  rubber  strands 
which  serve  as  the  motive  power  for  the  model, 
it  must  be  made  strong.  It  is  therefore  neces- 
sary to  exercise  care  and  judgment  in  making 
certain  that  the  different  units  that  make  up  the 
frame  are  rightly  proportioned  and  are  of  the 
proper  material.  Just  as  in  the  large  sized 
aeroplanes  there  are  many  types  of  bodies,  so 
there  are  many  different  types  of  frames  in  use 
in  model  construction,  but  the  standard,  and 
for  all  practical  purposes  the  best  frame,  re- 
sembles the  letter  A  in  shape,  hence  the  name 
A  type.  The  lightness  of  the  frame  depends 
entirely  on  the  materials  used  and  the  manner 
in  which  it  is  constructed. 

Some  model  flyers  use  but  a  single  stick  for 
the  frame,  but  generally  the  A  type  frame  is 
preferred  for  the  reason  that  it  is  more  durable, 
the  wings  can  be  more  securely  attached  to  it, 
and  that  it  is  possible  of  developing  very  much 
better  results. 

To  construct  such  an  A  type  frame  2  main 
sticks  to  serve  as  frame  side  members  are  neces- 


Members  of  the  Aero  Science  Club 


Members  of  the  Milwaukee  and  Illinois  Model  Aero  Clubs 


CONSTRUCTION  23 

sary  and  are  made  from  spruce.  Each  member 
should  be  36"  in  length,  y%"  in  depth  by  J4"  in 
width.  By  rounding  the  edges  and  smoothing 
the  various  surfaces  with  sandpaper  streamline 
effect  will  be  secured  and  will  add  to  the  ef- 
ficiency of  the  machine  as  well  as  to  its  appear- 
ance. When  the  side  members  are  placed  in  A 
formation  the  extremity  of  the  sticks  at  which 
they  meet  should  be  so  tapered  in  the  inner 
sides  that  when  they  meet  and  are  permanently 
fastened  the  result  will  be  a  continuance  of  the 
general  streamline  effect.  The  permanent 
fastening  of  the  frame  side  members  at  the 
point  of  the  A  may  be  accomplished  by  using 
either  strong  fish  glue  or  better,  a  good  water- 
proof glue  and  then  have  the  jointure  rein- 
forced by  securing  a  piece  of  3-32"  steel  wire  3" 
in  length  and  placing  the  center  of  it  at  the 
point  of  the  A,  afterwards  bending  the  wire 
along  either  outer  edge  of  the  frame  side  mem- 
bers, putting  as  much  pressure  on  the  wire  as 
the  strength  of  the  structure  will  permit;  after 
this  the  reinforced  jointure  should  have  thread 


24  MODEL  AEROPLANES 

wound  around  it  to  insure  even  greater 
strength.  About  y*"  of  the  wire  on  each  side 
of  the  point  should  be  left  clear  and  afterwards 
turned  into  a  loop  as  shown  in  diagram  6,  for 
the  purpose  of  attaching  the  hooks  that  hold 
the  rubber  strands.  To  hold  the  side  members 
apart  at  the  rear  end  and  for  a  propeller  brace, 
a  piece  of  bamboo  10"  long,  J^"  thick  by  J^" 
in  width  is  required  and  this  should  be  fastened 
to  the  extreme  rear  ends  of  the  frame  side  mem- 
bers, allowing  the  propeller  brace  to  protrude 
on  either  side  ij4"  as  illustrated.  To  put  the 
propeller  brace  in  position  a  slot  *^"  deep  by 
Y&"  wide  should  be  cut  into  the  rear  ends  of  the 
frame  side  members  for  the  reception  of  the 
propeller  brace.  After  the  brace  has  been 
placed  in  position  the  outer  edge  should  come 
flush  with  the  rear  ends  of  the  side  members. 
To  hold  the  brace  in  place  thread  and  glue 
should  be  used  in  the  same  manner  as  described 
for  the  point  of  the  frame  side  members.  Be- 
tween the  point  of  the  frame  and  the  propeller 
brace  two  bamboo  pieces,  one  9"  long  and  an- 


CONSTRUCTION 


Diagram  6 


26  MODEL  AEROPLANES 

other  2  1-3"  long,  should  be  used  as  braces  for 
the  general  strengthening  of  the  structure. 
The  longest  piece  should  be  secured  across  the 
top  of  the  frame  about  9"  from  the  rear  and 
the  shorter  piece  about  9"  from  the  point. 

When  these  two  braces  are  in  position  the 
next  matter  that  calls  for  the  attention  of  the 
constructor  is  the  matter  of  getting  into  posi- 
tion at  the  two  outer  extremities  of  the  pro- 
peller brace  bearings  for  the  propellers.  For 
this  purpose  two  pieces  of  3~32nd  inch  brass 
tubing,  each  y^th  of  an  inch  long,  should 
be  used,  and  should  be  fastened  to  the  under- 
side of  the  propeller  brace,  at  each  extremity  of 
that  brace,  by  the  use  of  thread  and  glue. 
Sometimes  greater  efficiency  is  secured  by  put- 
ting these  pieces  of  bronze  tubing  about  y^" 
from  the  end.  Some  model  constructors  make 
a  very  neat  jointure  here  by  soldering  the  piece 
of  tubing  to  a  strip  of  thin  brass,  which  is  bent 
over  the  end  of  the  propeller  brace  and  bound 
and  glued  thereon.  In  fastening  the  bronze 
tubing  to  the  propeller  brace  it  should  be  so 


CONSTRUCTION  27 

adjusted  that  it  will  run  parallel  to  the  side 
members  of  the  frame  and  will  therefore  offer 
the  least  possible  resistance  to  the  shaft  of  the 
propeller  when  the  rubber  strands  have  been 
attached. 

When  the  frame  has  been  completed  a  coat 
of  shellac  should  be  applied  to  the  entire  struc- 
ture to  render  it  damp-proof. 

ASSEMBLING 

The  proper  assembling  of  the  parts  of  the 
model  is  as  essential  to  good  results  as  is  the 
designing  and  making.  Parts,  although  prop- 
erly made,  if  improperly  placed  in  relation  to 
each  other  will  very  often  lead  to  trouble. 
Therefore  very  great  care  must  be  exercised  in 
the  assembling  process. 

When  all  the  parts  have  been  prepared  and 
are  ready  to  be  assembled  the  first  thing  that 
should  be  done  is  to  mount  the  propellers  in 
position.  This  must  be  done  very  carefully  on 
account  of  the  fact  that  the  propeller  shafts 
are  easily  bent  and  if  bent  the  result  is  consider- 


28  MODEL  AEROPLANES 

able  trouble,  for  such  a  bend  in  the  propeller 
shaft  will  cause  the  propeller  to  revolve  irregu- 
larly with  a  consequent  loss  of  thrust.  Before 
inserting  the  propeller  shafts  in  the  tubing  4 
washers  each  y$"  in  diameter  should  be  cut 
from  hard  metal,  and  a  hole  large  enough  for 
the  propeller  shaft  to  pass  through  should  be 
bored  in  the  center  of  each  washer.  The  metal 
washers  should  be  passed  over  the  straight  ends 
of  the  shafts  which  extend  from  the  rear  of 
the  tubing,  after  they  have  been  inserted  in  the 
tubing,  and  in  this  manner  the  cutting  into  the 
hubs  of  the  propellers  which  would  follow  is 
avoided.  The  propellers  are  now  to  be 
mounted  and  this  is  accomplished  by  allowing 
the  ends  of  the  shafts,  which  extend  out  from 
the  rear  of  the  tubing,  to  pass  through  the  hole 
in  the  hub  of  each  propeller.  In  mounting  the 
propellers  it  is  absolutely  necessary  to  have  the 
straight  edge  of  the  propellers  to  face  the  point 
or  front  end  of  the  model.  The  propeller 
shown  in  Fig.  4  of  diagram  i,  should  be 
mounted  on  the  left  side  of  the  frame  to  revolve 


CONSTRUCTION  29 

to  the  left,  while  the  propeller  shown  in  Fig.  i 
should  be  mounted  on  the  right  side  of  the 
frame  to  revolve  to  the  right.  When  the  pro- 
pellers have  thus  been  mounted  the  one-half 
inch  of  shafting  which  extends  out  from  the 
hubs  of  the  propellers  should  be  bent  over  to 
grip  the  propeller  hub  and  thereby  prevent  the 
shaft  from  slipping  during  the  unwinding  of 
the  rubber  strands.  For  the  reception  of  the 
rubber  strands  to  provide  motive  power  a  hook 
must  be  formed  in  each  shaft  and  this  can  be 
done  by  holding  securely  that  portion  of  the 
shaft  which  extends  toward  the  point  of  the 
model,  while  the  end  is  being  formed  into  a 
hook  as  illustrated  in  diagram  7. 

Eighty- four  feet  of  J^th"  flat  rubber  is 
necessary  to  propel  the  model.  This  should  be 
strung  on  each  side  from  the  hooks  (see  dia- 
gram) at  the  front  part  of  the  model  to  the  pro- 
peller shafts  at  the  rear  of  the  model.  In  this 
way  14  strands  of  rubber  will  be  evenly  strung 
on  each  side  of  the  frame.  To  facilitate  the 
winding  of  the  rubbers  two  double  hooks  made 


MODEL  AEROPLANES 


Diagram  7 


CONSTRUCTION  31 

of  3~32"  steel  wire  to  resemble  the  letter  S, 
as  shown  in  diagram  7,  should  be  made.  One 
end  of  this  S  hook  should  be  caught  on  the 
frame  hook,  while  the  other  end  is  attached  to 
the  strands  of  rubber,  and  to  prevent  the  pos- 
sible cutting  of  the  strands  a  piece  of  rubber 
tubing  is  used  to  cover  over  all  wire  hooks  that 
come  in  contact  with  the  rubber  strands  pro- 
viding propelling  power. 

The  wings  are  mounted  on  the  top  side  of  the 
frame  members  by  means  of  rubber  bands  and 
in  placing  them  upon  the  frame  it  should  be 
noted  that  the  entering  edge  of  each  wing  must 
face  the  point  or  front  of  the  model.  The 
wings  must  be  so  adjusted  on  the  frame  that 
they  result  in  perfect  side  balance  which  means 
that  there  is  an  even  amount  of  surface  on 
either  side  of  the  model.  To  secure  a  longi- 
tudinal balance  it  will  be  found  that  the  enter- 
ing edge  of  the  main  wing  should  be  placed 
approximately  8"  from  the  propeller  brace  or 
rear  of  the  model,  and  the  entering  edge  of  the 
small  wing  or  elevator  approximately  6"  from 


32  MODEL  AEROPLANES 

the  point.  But  it  is  only  by  test  flying  that  a 
true  balance  of  the  entire  model  can  be  obtained. 
To  give  the  necessary  power  of  elevation 
(or  lifting  ability)  to  make  the  model  rise,  a 
small  block  of  wood  about  i"  long  by  %" 
square  must  be  placed  between  the  entering 
edge  of  the  small  wing  and  the  frame  of  the 
model. 

After  the  wings  have  been  thus  adjusted  and 
a  short  test  flight  made  to  perfect  the  flying  and 
elevating  ability  of  the  model,  and  this  test 
flight  has  been  satisfactory,  the  model  is  ready 
for  launching  under  its  full  motive  power. 

LAUNCHING 

In  the  preliminary  trials  of  a  model  close  at- 
tention must  be  paid  to  the  few  structural  ad- 
justments that  will  be  found  to  be  necessary 
and  which  if  not  properly  and  quickly  remedied 
will  result  in  the  prevention  of  good  flights  or 
even  in  possible  wrecking  of  the  model.  Care- 
ful designing  and  construction  are  necessary 
but  it  is  equally  as  important  that  the  model 


Charles     W.     Meyers     and  Henry  Criscouli  and  his  five 
William  Hodgins  exhibit-       foot  model.    This   model 

may  be  disassembled  and 
packed  conveniently  in 
small  package 


ing  models   of   early   de- 
sign. 


Harry  G.  Schultz  hydroaeroplane 


CONSTRUCTION  33 

should  be  properly  handled  when  it  is  complete 
and  ready  for  flying. 

The  approximate  idea  of  the  balance  of  a 
model  can  be  secured  by  launching  it  gently  into 
the  air.  If  the  model  dives  down  point  first  it 
indicates  that  the  main  wing  should  be  moved 
a  little  toward  the  front.  If  it  rises  abruptly 
the  main  wing  should  be  moved  slightly  toward 
the  rear.  In  this  way  by  moving  the  wing  for- 
ward or  rearward  until  the  model  glides  away 
gracefully  and  lands  flat  upon  the  ground, 
proper  adjustment  of  the  balance  can  be  ef- 
fected. If  when  launching  from  the  hand  the 
model  should  curve  to  the  left  the  main  wing 
should  be  moved  slightly  to  the  left  of  the  frame 
members.  And  if  the  curve  is  to  the  right  the 
main  wing  should  be  moved  in  that  direction. 
This  process  can  be  continued  until  the  model 
flies  in  the  course  desired. 

The  winding  of  the  rubber  strands  to  get  the 
necessary  propelling  power  is  an  important  de- 
tail. The  model  should  be  firmly  held  by  some 
one  at  the  rear  with  the  thumb  on  either  side 


34  MODEL  AEROPLANES 

member,  pressing  down  on  the  jointure  and 
with  the  four  fingers  of  each  hand  gripping  the 
under  side  of  the  frame  members,  and  in  this 
way  holding  the  model  steady  and  until  the 
rubber  strands  have  been  sufficiently  wound. 
With  the  hands  in  this  position  the  propellers, 
of  course,  cannot  and  should  not  revolve.  The 
hooks  attached  to  the  rubber  strands  at  the 
point  or  front  of  the  model  should  be  detached 
from  the  side  members  and  affixed  to  the  hooks 
of  the  winder.  A  winder  may  be  made  from 
an  ordinary  egg  beater  as  is  shown  in  diagram 
8.  When  the  hooks  attached  to  the  rubber 
strands  at  the  point  of  the  model  have  been 
affixed  to  the  winder  the  rubbers  should  be 
stretched  four  times  their  ordinary  length 
(good  rubber  being  capable  of  being  stretched 
seven  times  its  length)  and  the  winding  com- 
menced, the  person  winding  slowly  moving  in 
towards  the  model  as  the  strands  are  wound. 
If  the  ratio  of  the  winder  is  5  to  I,  that  is  if  the 
rubber  is  twisted  five  times  to  every  revolution 
of  the  main  wheel  of  the  winder,  100  turns  of 


CONSTRUCTION 


35 


Diagram  8 


36  MODEL  AEROPLANES 

the  winder  will  be  sufficient  for  the  first  trial. 
This  propelling  power  can  be  increased  as  the 
trials  proceed.  When  the  winding  has  been 
accomplished  the  rubber  hooks  should  be  de- 
tached from  the  winder  hooks  and  attached  to 
the  hooks  at  the  front  of  the  side  members  as 
shown  in  the  diagram. 

In  preparation  for  launching,  the  model 
should  be  held  above  the  head,  one  hand  holding 
it  at  the  center  of  the  frame,  the  other  in  the 
center  of  the  propeller  brace  in  such  a  way  as 
to  prevent  the  propellers  from  revolving. 
When  the  model  is  cast  into  the  air  if  it  is  prop- 
erly adjusted  it  will  fly  straight  ahead. 

A  precaution  which  is  sometimes  worthy  of 
attention  before  the  launching  of  the  model 
under  its  full  power  is  to  test  out  the  propellers 
to  find  out  whether  or  not  they  are  properly 
mounted  and  whether  they  revolve  evenly  and 
easily.  To  do  this  the  rubber  strands  may  be 
given  a  few  turns,  enough  to  revolve  the  pro- 
pellers for  a  brief  period,  while  the  machine  is 
held  stationary.  If  the  shafts  have  been  prop- 


CONSTRUCTION  37 

erly  inserted  in  the  hubs  of  the  propellers  and 
have  not  been  bent  during  the  winding  of  the 
rubbers,  the  propellers  will  revolve  evenly  and 
readily.  If  the  propellers  revolve  unsteadily  it 
indicates  that  there  is  a  bend  in  the  propeller 
shafts  or  the  propellers  have  not  been  properly 
balanced.  If  the  trouble  is  a  bend  in  the  shaft, 
it  must  be  removed  before  the  model  is 
launched  on  actual  flight.  If  the  propeller 
does  not  revolve  freely  the  application  of  some 
lubrication  (such  as  vaseline)  to  the  shaft 
will  eliminate  this  trouble.  With  these  adjust- 
ments made  satisfactorily,  the  model  can  be 
launched  with  the  anticipation  of  good  flying. 

CHASSIS 

The  preceding  instructions  and  discussions 
have  dealt  with  different  parts  of  a  simple 
model  to  be  used  as  a  hand-launched  type  of 
model.  The  experience  which  will  come  as  the 
result  of  flying  this  type  of  model  for  a  period 
will  undoubtedly  tend  toward  a  desire  on  the 
part  of  the  constructor  to  make  his  model  more 


MODEL  AEROPLANES 


Diagram  9 


CONSTRUCTION  39 

nearly  represent  a  large  sized  aeroplane  and 
will  make  him  want  to  have  his  model  rise  from 
the  ground  under  its  own  power.  Such  a 
model  is  known  as  an  R.  O.  G.  type,  that  is, 
rises  off  the  ground.  To  meet  this  desire  all 
that  it  is  necessary  to  do  is  to  make  a  chassis, 
or  carriage,  which  can  be  secured  to  the  frame 
of  the  model,  and  with  extra  power  added,  will 
result  in  a  practical  R.  O.  G.  model.  In  con- 
structing such  a  chassis  or  carriage  it  is  neces- 
sary to  bear  in  mind  that  it  must  be  made  suffi- 
ciently strong  to  withstand  the  shock  and  stress 
which  it  will  be  called  upon  to  stand  when  the 
model  descends  to  the  ground. 

For  the  main  struts  of  the  chassis  two  pieces 
of  bamboo  each  9"  in  length  are  needed  and 
these  should  be  bent  over  i"  on  one  end  as 
shown  in  the  diagram,  that  they  may  be  fast- 
ened to  the  under  side  of  the  frame  members, 
one  on  either  side,  at  a  point  on  that  member 
12"  from  the  front.  Two  similar  pieces  of 
bamboo,  each  piece  about  7"  in  length,  are  re- 
quired to  act  as  braces  between  the  frame  mem- 


40  MODEL  AEROPLANES 

bers  and  the  main  chassis  struts.  Each  end  of 
each  of  the  braces  should  be  bent  over  in  the 
same  direction  and  in  the  same  manner  as  that 
described  for  the  main  strut  so  that  the  fasten- 
ing to  the  main  frame  member  and  the  main 
chassis  strut  may  be  accomplished.  Steam 
may  be  used  in  bending  the  ends  of  the  pieces 
of  bamboo.  To  make  the  landing  chassis  suffi- 
ciently stable  to  withstand  landing  shocks  a 
piece  of  bamboo  9"  should  be  fastened  from 
either  side  of  the  main  chassis  struts  at  the 
point  where  the  chassis  brace  on  either  side 
meets  with  main  strut.  The  ends  of  this  cross 
brace  should  be  bent  in  similar  fashion  to  the 
other  braces  to  enable  its  being  fastened  easily 
and  securely. 

Two  small  wheels  constitute  the  running  gear 
for  the  front  part  of  the  chassis,  for  which  two 
pieces  of  1-16"  steel  wire  each  2l/±"  long 
are  required.  These  small  wires  are  fastened 
to  the  bottom  ends  of  the  main  struts,  and  to 
accomplish  this  the  wire  should  be  bent  in  the 
center  at  right  angles ;  one  leg  of  the  angle  is 


CONSTRUCTION  41 

attached  to  the  bottom  end  of  the  main  strut  as 
shown  in  the  diagram.  Disks  for  wheels  may 
be  cut  from  a  bottle  cork  which  should  be  ^4" 
in  diameter  by  approximately  y\"  in  thickness. 
The  edges  should  be  rounded  off  to  prevent 
chipping.  Before  mounting  the  wheels  on  the 
axles  which  have  been  provided  by  the  wires  at- 
tached to  the  bottom  of  the  main  struts,  a  piece 
of  bronze  tubing  3-32"  inside  diameter  and 
3-16"  long  should  be  inserted  in  the  center  of 
each  disk.  To  secure  the  least  possible  resist- 
ance on  the  revolutions  of  the  wheels,  there 
should  be  placed  on  the  wire  axles  pieces  of 
bronze  tubing  similar  in  diameter  and  y%"  in 
length  on  either  side  of  the  wheel  (see  illustra- 
tion). When  the  wheel  is  thus  placed  in  posi- 
tion with  the  pieces  of  bronze  tubing  on  either 
side  about  %"  of  the  axle  wire  will  extend  from 
the  outward  end  of  the  outside  piece  of  tubing. 
This  should  be  bent  over  the  tubing  to  prevent 
its  falling  off  and  at  the  same  time  hold  the 
wheel  securely  in  position. 

For  the  rear  skid  a  piece  of  bamboo  6"  long 


42  MODEL  AEROPLANES 

is  used,  one  end  of  which  is  curved  as  in  a 
hockey  stick  so  that  it  will  glide  smoothly  over 
the  ground.  The  other  end  of  the  rear  skid 
should  be  bent  over  about  y*"  so  that  it  can  be 
securely  fastened  to  the  propeller  braces,  as  il- 
lustrated in  the  diagram.  Two  7"  pieces  of 
bamboo  are  required  to  act  as  braces  for  the 
rear  skid.  Both  ends  of  each  brace  strut  are 
bent  over  J4"  in  the  same  direction,  one  end  of 
each  strut  is  securely  fastened  to  a  side  mem- 
ber 3"  from  the  rear  and  the  other  end  of  each 
strut  is  fastened  to  the  rear  skid,  at  their  point 
of  meeting  as  shown  in  diagram  9,  the  method 
of  attaching  being  the  same  as  in  the  case 
of  the  forward  portion  of  the  chassis.  All 
joining  should  be  accomplished  by  first  gluing 
the  braces  and  then  binding  with  thread. 
When  completed,  the  rear  skid  should  glide 
along  the  ground  in  bobsled  fashion,  thus  pre- 
venting the  propellers  from  hitting  the  ground. 
In  making  such  a  chassis  or  carriage  the  en- 
deavor should  be  made  to  use,  as  near  as  pos- 
sible, the  same  weight  of  material  on  either  side 


CONSTRUCTION 


43 


Diagram  10 


44  MODEL  AEROPLANES 

of  the  model  so  as  little  interference  as  possible 
will  be  made  with  the  general  balance  of  the 
model  in  flight. 

PONTOONS 

Having  satisfactorily  developed  the  hand 
launched  model  and  the  model  rising  off  the 
ground  under  its  own  propulsion  the  construc- 
tor will  next  turn  his  mind  to  the  question  of 
having  his  model  rise  under  its  own  power  from 
the  surface  of  the  water  in  the  fashion  of  pas- 
senger-carrying hydros  and  flying  boats.  This 
will  be  accomplished  by  the  use  of  pontoons  at- 
tached to  a  specially  designed  chassis. 

Three  pontoons  are  necessary  and  these 
should  be  made  as  light  as  possible.  Each  pon- 
toon should  be  made  6"  long,  i"  deep  toward 
the  forward  part,  by  £4"  at  the  rear  and  2" 
wide.  The  side  members  of  each  pontoon  are 
made  from  pieces  of  thin  white  pine  wood 
i-32nd  of  an  inch  thick,  slightly  curved  up  at 
the  front  and  sloped  down  toward  the  rear. 
Small  niches  should  be  made  on  the  top  and  bot- 
tom sides  of  the  pontoons  into  which  the  cross 


C.  V.  Obst  World  record 
flying  boat 


Twin  tractor  Hydroaeroplane 
designed  and  constructed 
by  George  F.  McLaughlin 


Louis  Bamberger's  hydro  about  to 
leave  surface  of  water 


CONSTRUCTION  45 

braces  are  inserted  and  glued.  Further  refer- 
ence to  diagram  10  will  show  that  at  the  ex- 
treme forward  end  of  the  sides  a  cut  is  made 
large  enough  to  receive  a  flat  piece  of  spruce 
1-16"  wide.  Another  cut  of  the  same  dimen- 
sions is  made  at  the  extreme  rear  end.  Still 
further  cuts  are  made  on  the  top  and  bottom 
sides  of  the  pontoons,  the  forward  cuts  meas- 
uring \y2"  from  the  front  and  the  rear  cuts 
i  J4"  from  the  rear,  to  join  the  sides  of  the  pon- 
toons as  illustrated  in  diagram  10.  Six  pieces 
of  i -i 6"  flat  spruce  are  required  for  the  rear 
pontoon,  the  ends  of  which  are  held  in  posi- 
tion by  glue.  For  the  forward  pontoon  only  4 
braces  are  required  in  so  far  as  the  ends  of  the 
two  main  brace  spars  of  the  forward  part  of 
chassis  are  inserted  in  the  cuts  on  the  top  sides 
of  the  pontoon.  These  brace  spars  measure  10 
inches  in  length  and  are  made  from  bamboo 
2/8  th  inch  in  diameter,  which  necessitates  en- 
largement of  the  cuts  on  the  top  sides  of  the 
forward  pontoons  so  that  the  extreme  ends  of 
the  spars  can  be  inserted  in  the  cuts  in  the  place 


46  MODEL  AEROPLANES 

of  the  braces.  To  complete  the  rear  pontoon 
and  prepare  it  for  covering,  three  strips  of 
y%"  bamboo  are  required  for  struts.  Two  of 
these  strips  should  measure  9"  in  length  and 
should  be  attached  to  the  front  of  the  pon- 
toon on  the  inner  side  as  shown  in  diagram  10. 
Thread  and  glue  should  be  used  in  attaching 
the  ends  of  the  strips  to  the  pontoon.  To  en- 
able fastening  to  the  frame  the  upper  ends  of 
the  bamboo  strips  should  be  bent  over  about 
y2".  The  third  strip  should  measure  8"  in 
length  and  is  attached  to  the  upper  and  lower 
braces  toward  the  front  of  the  pontoon  as 
shown  in  the  diagram.  It  is  necessary  that 
this  strip  be  secured  in  the  approximate  center 
of  the  pontoon  to  insure  a  good  balance.  For 
the  purpose  of  securing  the  upper  end  of  the 
third  strut  to  the  center  of  the  propeller  brace 
a  piece  of  wire  ij^"  long  should  be  secured  to 
the  upper  end  of  the  strut  and  looped  as  shown 
in  diagram  10.  The  three  pontoons  should 
now  be  covered  with  fiber  paper  and  it  is  neces- 
sary to  exercise  care  to  avoid  punctures.  For 


CONSTRUCTION  47 

the  purpose  of  coating  the  fiber  paper  to  render 
it  waterproof,  a  satisfactory  solution  can  be 
made  by  mixing  banana  oil  with  celluloid  until 
it  has  attained  the  desired  thickness,  after 
which  it  should  be  applied  to  the  covering  of 
the  pontoons  with  a  soft  brush. 

For  the  main  strut  of  the  forward  portion  of 
the  chassis  two  pieces  of  Y§"  bamboo,  each 
11"  in  length,  are  required  and  these  should 
be  bent  over  i"  on  one  end  as  shown  in  the 
diagram,  that  they  may  be  fastened  to  the  un- 
der side  of  the  frame  members,  one  on  either 
side  at  a  point  on  that  member  n"  from  the 
front.  Two  similar  pieces  of  bamboo,  each 
piece  8"  in  length,  are  required  to  act  as  braces 
between  the  frame  members  and  the  main 
chassis  struts.  Each  end  of  tfye  braces  should 
be  bent  over  in  the  same  direction  and  in  the 
same  manner  as  that  described  for  the  main 
struts  so  that  the  fastening  to  the  main  frame 
member  and  the  main  chassis  struts  may  be 
accomplished.  Steam  or  an  alcohol  lamp  may 
be  used  in  bending  the  ends  of  the  pieces  of 


48  MODEL  AEROPLANES 

bamboo.  To  make  the  chassis  sufficiently 
stable  a  piece  of  bamboo  7^"  should  be  fast- 
ened from  either  side  of  the  main  chassis  struts 
at  the  point  where  the  chassis  brace  on  either 
side  meets  With  the  main  strut.  The  ends  of 
this  cross  brace  should  be  bent  in  similar  fash- 
ion to  the  other  braces  to  enable  its  being 
fastened  easily  and  permanently. 

For  the  accommodation  of  the  pontoons  two 
strips  of  flat  steel  wire,  each  4"  in  length, 
should  be  attached  to  the  ends  of  the  main 
struts,  about  one  inch  from  the  bottom,  the 
farthest  ends  should  be  bent  to  grip  the  second 
spar  which  joins  the  pontoons.  Note  diagram 
10. 

To  further  strengthen  the  chassis  a  strip  of 
flat  steel  wire  sufficiently  long  enough  should  be 
bent  so  that  %"  of  the  central  portion  can  be 
securely  fastened  to  the  center  of  the  cross 
brace  as  shown  in  diagram  10.  The  two 
outer  ends  should  be  bent  down  and  are  fas- 
tened to  the  wires  which  are  attached  to  the  bot- 
tom ends  of  the  struts.  This  method  of  at- 


Erwin  B.  Eiring  about  to  release  R.  O.  G.  Model.  (Note 
manner  of  holding  propellers.)  Kennith  Sedgwick,  tractor 
record  holder  Milwaukee  Model  Club.  Courtesy  Gilbert 
Counsell. 


Waid  Carl  releasing  R.  O.  G.  Model.    Courtesy  Edward 
P.  Warner. 


CONSTRUCTION  49 

taching  the  forward  pontoons  enables  the  con- 
structor to  adjust  them  to  any  desired  angle 
and  also  detach  them  when  not  in  use. 

A  model  hydroaeroplane  is  one  of  the  most 
interesting  types  of  models  and  if  properly 
taken  care  of  will  afford  the  constructor  many 
pleasant  moments. 

LAUNCHING   AN    R.    O.    G.    OR    MODEL 
HYDROAEROPLANE 

Although  the  method  of  determining  the  bal- 
ance of  an  R.  O.  G.  or  a  model  hydroaeroplane 
is  exactly  the  same  as  that  of  a  hand  launched 
model,  the  manner  of  launching  is  somewhat 
different.  Instead  of  holding  the  model  one 
hand  in  the  center  of  the  frame  and  the  other  at 
the  rear  as  in  the  case  of  the  hand  launched 
model,  in  launching  an  R.  O.  G.  or  hydro,  the 
model  should  be  rested  upon  the  ground  or 
water,  as  the  case  may  be,  with  both  hands 
holding  tightly  to  the  propellers.  Then  when 
about  to  let  the  model  go  release  both  propellers 
instantly.  If  the  model  has  sufficient  power 


50  MODEL  AEROPLANES 

and  it  has  been  properly  adjusted  it  will  glide 
over  the  surface  of  the  ground  or  water  for  a 
short  distance,  then  rise  into  the  air.  Should 
the  model  fail  to  rise  into  the  air  additional 
strands  of  rubber  should  be  added,  after  which 
it  should  be  rewound  and  a  second  attempt 
made. 

Should  the  model  fail  to  respond  after  the  ad- 
dition of  extra  rubber,  the  indications  are  that 
something  requires  further  adjustment.  Per- 
haps the  pontoons  need  further  elevation  if  the 
model  is  a  hydro,  or  if  it  be  an  R.  O.  G.  model 
the  forward  wing  may  require  an  increase  of 
elevation.  In  any  event  the  model  should  be 
carefully  examined  and  adjustments  made 
where  necessary,  after  which  the  model  should 
be  tested  for  balance  and  elevation.  If  satis- 
fied with  the  behavior  of  the  model  after  test 
flights  have  been  made,  another  attempt  should 
be  made  to  launch  the  model  from  the  ground 
or  water. 

On  no  account  try  to  fly  the  model  in  the 
house,  or  see,  supposing  the  model  is  of  the  R. 


CONSTRUCTION  51 

O.  G.  type,  if  it  will  rise  from  the  dining  room 
floor.  This  advice  may  seem  unnecessary,  but 
it  is  not  so,  for  there  has  been  quite  a  number 
of  instances  in  which  the  above  has  been  done, 
nearly  always  with  disastrous  results,  not  al- 
ways to  the  model,  more  often  to  something  of 
much  greater  value.  The  smashing  of  win- 
dows has  often  resulted  from  such  attempts, 
but  generally  speaking  pictures  are  the  worst 
sufferers.  It  is  equally  unwise  to  attempt  to 
fly  the  model  in  a  garden  in  which  there  are 
numerous  obstructions,  such  as  trees  and  so 
forth.  A  wrecked  model  is  very  often  the  re- 
sult of  such  experimenting.  The  safest  way  to 
determine  the  flying  ability  of  any  model  is  to 
take  it  out  in  an  open  field  where  its  flight  is 
less  apt  to  be  interrupted. 


WORLD  RECORD  MODELS 

THE  LAUDER  DISTANCE  AND 
DURATION  MODEL 

AFTER  many  months  of  experimentation  Mr. 
Wallace  A.  Lauder  succeeded  in  producing  a 
model  that  proved  to  be  one  of  his  most  suc- 
cessful models.  But  a  few  years  ago  flights 
of  1000  feet  with  a  duration  of  60  seconds  were 
considered  remarkable.  But  so  rapid  has  been 
the  development  of  the  rubber  strand  driven 
model  that  to-day  it  is  hardly  considered  worth 
while  to  measure  a  flight  of  1000  feet,  espe- 
cially in  contests  where  models  fly  over  2500 
feet  or  3537  feet  which  was  the  distance  flown 
by  Mr.  Lauder's  model  during  one  of  the  con- 
tests of  the  National  Model  Aeroplane  competi- 
tion of  1915.  Mr.  Lauder's  model  on  several 
occasions  made  flights  of  over  3500  feet  with  a 
duration  in  each  event  of  over  195  seconds.  It 

is  therefore  to  be  remembered  that  this  model 

52 


LAUDER  WORLD  RECORD  MODEL     53 

is  both  a  distance  and  duration  model,  both 
qualities  being  seldom  found  in  one  model. 

Reference  to  the  accompanying  drawing 
will  give  a  clear  idea  of  the  constructional  de- 
tails. 

The  frame  or  fuselage  consists  of  two  side 
members  40"  in  length,  of  straight  grained 
spruce.  At  the  center  each  member  is  of  ap- 
proximately cross  section,  and  is  J4"  m  di- 
ameter. The  members  taper  to  about  3-16"  at 
the  ends,  the  circular  cross  section  being  main- 
tained throughout.  The  frame  is  braced  by  a 
strip  of  bamboo  of  streamline  form,  extending 
from  one  side  member  to  the  other,  18"  from 
the  apex  of  the  frame.  The  ends  of  this  frame 
are  bent  to  run  parallel  to  the  side  members  of 
the  frame  where  they  are  secured  by  binding 
with  silk  thread  and  gluing.  Piano  wire  hooks 
are  also  secured  to  the  side  members  of  the 
frame  adjacent  the  ends  of  the  cross  brace,  and 
from  these  hooks  extend  wires  of  steel  (No.  2 
music  wire)  which  run  diagonally  to  the  rear 
brace  or  propeller  spar  where  they  are  secured. 


54 


MODEL  AEROPLANES 


Blank 


Diagram  n 


LAUDER  WORLD  RECORD  MODEL      55 

The  frame  is  braced  further  by  an  upwardly 
arched  strip  of  bamboo,  as  shown  in  diagram 
1 1,  this  strip  being  2  J^?"  in  height.  At  the  top 
of  this  brace  are  two  bronze  strips  of  No.  32 
gauge  brass,  one  above  the  other,  one  on  top  of 
the  brace  and  the  other  below. 

Adjacent  the  ends  of  these  strips  of  metal  are 
perforations  through  which  pass  bracing  wires, 
one  of  which  wires  run  to  the  front  of  the 
frame  where  a  hook  is  mounted  for  its  recep- 
tion, and  the  other  two  wires  extend  to  the  rear 
of  the  frame  where  they  are  secured  to  the  pro- 
peller brace.  The  propeller  brace  consists  of 
a  strip  of  streamlined  spruce  n^4"  in  length, 
the  propellers  being  at  an  angle,  thus  clearance 
is  allowed  J4"  wide  at  the  center,  tapering  to 
3-16"  at  the  ends.  The  ends  of  the  propeller 
brace  extend  out  one  inch  from  the  side  mem- 
bers of  the  frame,  to  allow  room  for  the  rubber 
strands  to  be  used  as  motive  power.  In  order 
to  avoid  slotting  the  ends  of  the  side  members 
of  the  frame  so  that  the  propeller  brace  can  be 
secured  therein,  thin  strips  of  bamboo  are  se- 


56  MODEL  AEROPLANES 

cured  above  and  below  the  end  of  each  side 
member,  by  binding  with  silk  thread  and  glu- 
ing, the  space  between  these  bamboo  strips  be- 
ing utilized  for  the  brace  which  is  securely 
bound  and  glued  therein.  The  propeller  bear- 
ings consist  of  strips  of  very  thin  bronze  (No. 
32  gauge),  about  3-16"  in  width,  bent  over 
$/%"  strips  of  German  silver  tubing,  the  tubing 
being  soldered  to  the  bronze  strips  and  the 
propeller  brace,  which  fits  between  the  up- 
per and  lower  portions  of  the  bronze  strips,  is 
securely  bound  and  glued  thereto. 

The  propellers  are  cut  from  solid  blocks  of 
pine,  and  are  12"  in  diameter.  The  blade,  at 
its  widest  portion,  measures  iJMs".  The  blades 
are  cut  very  thin,  and  in  order  to  save  weight, 
they  are  not  shellacked  or  painted. 

The  propeller  shafts  are  of  piano  wire  (No. 
20  size)  to  fit  the  tubing  used  in  the  bearings, 
pass  through  the  propellers  and  are  bent  over 
on  the  outer  side  to  prevent  turning.  A  few 
small  bronze  washers  are  interposed  between 
the  propellers  and  the  outer  ends  of  the  tubing 


Wallace  A.  Lauder  distance  and  duration  model 


Wallace  A.  Lander  R.  O.  G.  Model 


LAUDER  WORLD  RECORD  MODEL      57 

to  minimize  friction  when  the  propellers  are  re- 
volving. Twelve  strands  of  rubber  are  used 
for  each  propeller,  the  rubber  being  j£"  flat. 

The  wings  are  both  double  surfaced,  and  are 
of  the  swept  back  type.  The  span  of  the  main 
wing  is  28%",  with  a  chord  of  6y2".  The  ele- 
vator has  a  span  of  15"  with  a  chord  of  4?4". 
The  main  wing  has  eleven  double  ribs,  these 
ribs  being  built  up  on  mean  beams  of  spruce 
I- 1 6"  x  3-16",  the  front  beam  being  placed  i  J4" 
from  the  entering  edge,  and  the  second  beam 
being  2"  back  from  the  front  beam.  The  enter- 
ing and  trailing  edges  are  formed  from  a  sin- 
gle strip  of  thin  split  bamboo,  all  the  joints  be- 
ing made  by  binding  with  thin  silk  and  gluing. 

The  elevator  is  constructed  in  like  manner, 
except  that  it  only  has  seven  ribs,  and  the  meas- 
urements are  as  above  set  forth.  Both  planes 
are  covered  with  goldbeater's  skin,  sometimes 
known  as  "Zephyr"  skin,  which  is  first  glued  in 
place  and  then  steamed,  which  tightens  the 
same  on  the  plane,  and  given  a  coat  of  prepara- 
tion used  for  this  purpose. 


THE  HITTLE  WORLD  RECORD 
MODEL 

(SINGLE  TRACTOR  MONOPLANE,  116  SECONDS 
DURATION  RISING  FROM  WATER) 

THE  Kittle  World  record  model  hydroaero- 
plane, designed  and  constructed  by  Mr.  Lindsay 
Kittle  of  the  Illinois  Model  Aero  Club,  is  per- 
haps one  of  the  most  interesting  types  of  models 
yet  produced.  The  establishing  of  this  record 
illustrates  the  value  of  careful  designing  and 
construction  and  offers  to  the  beginner  an  ex- 
ample which  might  be  followed  if  good  results 
are  sought.  In  having  broken  the  world's 
model  hydroaeroplane  record  with  a  tractor 
type  model  Mr.  Kittle  accomplished  a  feat  of 
twofold  importance.  First,  in  having  ad- 
vanced the  possibilities  of  the  tractor  model, 
and,  second,  in  illustrating  the  value  of  scien- 
tific construction.  The  previous  record  for 

58 


KITTLE  WORLD  RECORD  MODEL     59 

this  type  of  model  has  been  but  29  seconds,  just 
one-fourth  of  the  duration  made  by  Mr.  Hit- 
tie's  model. 

Mr.  Hittle's  model  shows  many  new  and 
original  features  not  hitherto  combined  on  any 
one  model.  Note  diagram  12.  The  model  is 
of  extremely  light  weight,  weighing  complete 
but  1.75  ounces.  The  floats  and  their  attach- 
ments have  been  so  designed  as  to  offer  the 
least  possible  wind  resistance.  In  fact  every 
possible  method  was  utilized  in  order  to  cut 
down  weight  and  resistance  on  every  part  of 
the  model.  As  a  result  of  this  doing  away  with 
resistance  an  excellent  gliding  ratio  of  8^4  to  I 
has  been  obtained. 

For  the  motor  base  of  the  model  a  single  stick 
of  white  pine  %"  deep  and  45"  in  length  is  used. 
On  the  front  end  the  bearing  for  the  propeller 
is  bound  with  silk  thread  and  a  waterproof  glue 
of  the  constructor's  own  composition  being 
used  to  hold  it  secure.  For  the  bearing  a  small 
light  weight  forging  somewhat  in  the  shape  of 
the  letter  "L"  is  used,  this  being  made  stream- 


60  MODEL  AEROPLANES 

line.  At  the  rear  end  of  the  motor  base  is  at- 
tached a  piano  wire  hook  for  the  rubber.  The 
stabilizer  consisting  of  a  segment  of  a  circle 
measuring  12"  x  8"  is  attached  to  the  under 
side  of  the  motor  base.  The  rudder  measuring 
3^"X3^"  is  attached  to  the  stabilizer  at  the 
rear  of  the  motor  base. 

The  wing  is  built  up  of  two  beams  of  white 
pine  with  ribs  and  tips  of  bamboo  and  has  an 
area  of  215  square  inches 

The  wing  which  has  a  total  span  of  43"  and 
a  chord  of  5^"  is  built  up  of  two  beams  of 
white  pine  with  ribs  and  tips  of  bamboo  and 
has  a  total  area  of  215  square  inches.  The 
wing  is  given  a  small  dihedral  and  the  wing  tips 
are  slightly  upturned  at  the  rear. 

The  trailing  edge  is  longer  than  the  entering 
edge  the  ribs  being  placed  somewhat  oblique  in 
order  to  secure  an  even  spacing.  The  wing  is 
attached  to  the  frame  by  two  small  bamboo 
clips  which  hold  it  rigidly  and  permit  easy  ad- 
justment and  is  set  at  an  angle  of  about  4 
degrees  with  the  line  of  thrust.  Both  the 


KITTLE  WORLD  RECORD  MODEL     61 


PlatvVietS. 


Diagram  12 


62  MODEL  AEROPLANES 

floats  which  take  practically  the  whole  weight 
of  the  machine  are  situated  directly  under  the 
wing  just  far  enough  behind  the  center  of 
gravity  to  prevent  the  model  from  tipping  back- 
ward. These  floats  are  attached  to  the  motor 
base  by  means  of  streamlined  bamboo  struts. 
Bamboo  is  also  used  in  the  construction  of  the 
float  frames.  A  single  float  of  triangular  sec- 
tions is  situated  just  behind  the  propeller.  The 
entire  weight  of  the  floats  and  their  attach- 
ments is  but  .23  ounces. 

The  propeller  which  consists  of  four  blades 
is  built  up  of  two  propellers  joined  together  at 
the  hubs  and  securely  glued,  the  completed  pro- 
peller having  a  diameter  of  10"  with  a  theoreti- 
cal pitch  of  14".  The  blades  are  fairly  nar- 
row, tapering  almost  to  a  point  at  the  tips. 
The  propeller  is  driven  by  five  strands  of  %6th" 
strip  rubber  at  about  760  r.  p.  m.  when  the 
model  is  in  flight.  At  the  time  when  the  model 
made  its  record  flight  of  116  seconds  the  rubber 
was  given  1500  turns  which  is  not  the  maxi- 
mum number  of  turns.  At  other  times  the 


KITTLE  WORLD  RECORD  MOQEL     63 

model  has  flown  satisfactorily  with  less  turns 
of  the  rubber.  While  in  the  air  the  model  flies 
very  slow  and  stable  notwithstanding  its  light 
weight  and  large  surface.  On  three  occasions 
the  model  has  made  durations  of  approximately 
90  seconds  which  rather  dispenses  the  possi- 
bility of  its  being  termed  a  freak. 


THE  LA  TOUR  FLYING  BOAT 

ONE  of  the  most  notable  results  of  the  Na- 
tional Model  Aeroplane  Competition  of  1915 
was  the  establishing  of  a  new  world's  record 
for  flying  boats.  Considering  that  the  model 
flying  boat  is  a  difficult  type  of  model  to  con- 
struct and  fly,  the  establishing  of  this  new 
world  record  of  43  seconds  is  remarkable. 
Credit  for  this  performance  is  due  Mr.  Robert 
La  Tour  of  the  Pacific  Northwest  Model  Aero 
Club,  who  designed,  constructed  and  flew  the 
model  flying  boat  which  is  herewith  described 
and  illustrated.  Diagram  13. 

The  frame  is  made  of  laminated  spruce  40" 
in  length,  made  of  two  strips  glued  together. 
They  are  %"x%"  at  the  center  tapering  to 
%e"  x  %"  at  the  ends.  The  cross  braces  are  of 
split  bamboo  and  are  fastened  to  the  frame  side 
members  by  bringing  them  to  a  wedge  at  the 
ends  and  then  inserting  them  into  slots  in  the 

64 


LA  TOUR  FLYING  BOAT  65 

sides  of  the  frame  side  members  and  are  finally 
drilled  and  bound  to  the  latter.  The  rear  brace 
is  of  streamlined  spruce  }4"x  j£";  this  butts 
against  the  frame  side  members  and  is  bound 
to  them.  The  propeller  accommodations  are 
made  of  brass. 

The  propellers  are  10"  in  diameter  with  a  19" 
pitch.  These  are  carved  from  a  block  of 
Alaska  cedar  i%"  wide  by  ft"  thick.  Of 
course  the  propellers  may  also  be  made  from 
white  pine.  To  turn  the  propellers  15  strands 
of  Y%"  flat  rubber  are  used. 

Bamboo  about  VIG"  square  is  used  to  obtain 
the  outline  of  the  wings.  The  main  wing  has 
a  span  of  33"  with  a  chord  of  5  T/2  ".  Split  bam- 
boo is  used  for  the  making  of  the  9  ribs.  The 
wing  spar  or  brace  is  of  spruce  %e"  x  %"  and  is 
fastened  below  the  ribs  as  illustrated  in  dia- 
gram 13.  The  elevator  is  constructed  in  like 
manner  but  has  a  span  of  only  I7"x424"  and 
has  only  5  ribs.  A  block  %"  high  is  used  for 
elevation.  Both  wings  have  a  camber  of  J4" 
and  are  covered  on  the  upper  side  with  silk 


66 


MODEL  AEROPLANES 


Diagram  13 


LA  TOUR  FLYING  BOAT  67 

doped  with  a  special  varnish  and  a  few  coats  of 
white  shellac. 

The  boat  is  20"  long,  3"  in  width  and  shaped 
as  shown.  The  slip  is  ^2"  deep  and  is  located 
7"  from  the  bow.  The  rear  end  is  brought 
down  steeply  to  avoid  the  drag  of  the  water  on 
this  point  when  the  boat  is  leaving  the  surface 
of  the  water.  Spruce  %4ths  of  an  inch  thick  is 
used  for  the  making  of  the  sides,  but  the  cross 
bracing  is  of  slightly  heavier  material,  there  be- 
ing six  braces  used  throughout.  The  rear 
brace  is  much  heavier  in  order  to  withstand  the 
pull  of  the  covering  and  to  receive  the  ends  of 
the  wire  connections.  The  outriggers  or  bal- 
ancing pontoons  are  constructed  of  the  same 
material  as  that  of  the  boat  and  are  held  to- 
gether by  a  spruce  beam  18"  long,  y2n  wide  by 
%e"  thick,  streamlined.  This  beam  is  fastened 
to  the  boat  by  means  of  three  brads  to  permit 
changing  if  necessary.  The  lower  edges  of  the 
outriggers  should  clear  the  water  abo,ut  J^"  be- 
fore the  steps  on  the  boat  leave  the  water.  The 
boat  and  outriggers  are  covered  with  silk, 


68  MODEL  AEROPLANES 

shrunk  with  a  special  solution  and  then  coated 
several  times  with  white  shellac.  It  is  a  good 
plan  to  shellac  the  interior  walls  of  the  boat  and 
pontoons  before  covering  to  prevent  them  from 
losing  their  form  by  becoming  soft  from  the 
influence  of  water  in  the  case  of  a  puncture. 

The  boat  is  connected  to  the  frame  at  its 
front  by  two  steel  wires,  their  ends  being  in- 
serted into  the  cross  members  of  the  boat,  and 
then  brought  up  along  the  sides,  crossed  and 
then  bound  to  the  frame.  A  similar  pair  of 
connecting  wires  are  used  to  connect  the  rear 
end  of  the  boat  to  the  rear  end  of  the  frame. 
A  U-shaped  wire  is  bound  to  the  outrigger 
beam  and  frame.  A  single  diagonal  strip  of 
bamboo  is  also  fastened  to  the  outrigger  beam 
with  a  brad,  its  upper  end  being  bound  to  the 
cross  bracing  of  the  frame,  making  a  very  solid 
connection. 

Under  ideal  weather  conditions  this  model 
will  fly  on  12  strands  of  rubber  with  the  possi- 
bility of  a  better  duration  than  has  been  made. 
But,  however,  with  15  strands  the  model  will 


LA  TOUR  FLYING  BOAT  69 

rise  at  every  attempt.  More  rubber,  however, 
causes  the  bow  of  the  boat  to  nose  under  and  to 
accommodate  this  increase  of  power  the  boat 
should  be  lengthened. 


THE  COOK  NO.  42  WORLD 
RECORD  MODEL 

(TWIN    PROPELLER   HYDROAEROPLANE,    IOO.6 
SECONDS   RISING   FROM    WATER) 

DURING  the  National  Model  Aeroplane  Com- 
petition of  1915  held  under  the  auspices  of  the 
Aero  Club  of  America,  a  number  of  new  world 
records  were  established,  one  of  which  was  for 
twin  propeller  hydroaeroplanes.  The  credit 
for  this  record  is  due  Mr.  Ellis  C.  Cook  of  the 
Illinois  Model  Aero  Club,  who  succeeded  in 
getting  his  model  hydroaeroplane — which  by 
the  way  is  a  rather  difficult  type  of  model  to 
operate — to  rise  from  the  water  and  remain  in 
the  air  for  a  duration  of  100.6  seconds.  This 
model  is  of  the  common  A  frame  design  with 
the  floats  or  pontoons  arranged  in  the  familiar 
fashion,  two  forward  and  one  aft.  The  model 
is  fairly  light,  weighing,  when  complete,  3.33 

70 


THE  COOK  NO.  42  MODEL  71 

ounces,  ^  ounce  of  which  is  made  up  in  rubber 
strands  for  motive  power.     Diagram  14. 

The  frame  is  made  of  two  sticks  of  white 
pine  for  side  members,  each  member  measuring 
$81A"  in  length,  5/i6"  in  depth,  by  H"  in  width. 
These  are  cut  to  taper  toward  the  ends  where 
they  are  only  Vs"  in  width  by  %e"  in  depth  in  the 
front  and  rear  respectively.  Three  "X"  strips 
of  streamlined  bamboo  measuring  %e"  in  width 
by  %4ths  of  an  inch  in  depth,  are  used  for  brac- 
ing the  frame  between  the  front  and  rear  and 
are  arranged  as  shown  in  diagram  14.  The 
propeller  bearings  are  of  small  streamlined 
forgings  of  light  weight,  and  are  bound  to  the 
rear  end  of  each  side  member  first  by  gluing, 
then  binding  around  with  thread.  The  front 
hook  is  made  of  No.  16  piano  wire  and  is  bound 
to  the  frame  as  shown  in  diagram  14.  The 
chassis  which  holds  the  floats  or  pontoons  is 
made  of  %2"  bamboo  bent  to  shape  and  bound 
to  the  frame  members.  By  the  use  of  rubber 
strands  the  floats  are  attached  to  the  chassis; 


72  MODEL  AEROPLANES 

the  forward  ones  being  attached  so  that  angle 
may  be  adjusted. 

The  main  wing  has  a  span  of  36"  and  a 
chord  of  5"  and  is  constructed  of  two  white 
pine  beams  each  39"  long,  with  bamboo  wing 
tips.  The  ribs,  seven  in  number,  are  also  made 
of  bamboo  and  are  spaced  along  the  edges  of 
the  wing  at  a  distance  of  4^"  apart.  The 
"elevator"  or  front  wing  has  a  span  of  14"  and 
a  chord  of  3)4">  the  framework  of  which  is 
made  entirely  of  bamboo.  The  entering  edge 
of  this  wing  is  given  a  slightly  greater  dihedral 
so  that  the  angle  of  incidence  at  the  tips  is 
greater  than  at  the  center.  By  this  method  the 
added  incidence  in  the  front  wing  is  obtained. 
By  the  use  of  rubber  bands  both  wings  are  at- 
tached to  the  frame. 

The  two  forward  floats  are  spaced  eight  in- 
ches apart  and  are  of  the  stepped  type,  the  step 
being  3%"  from  the  front  and  has  a  depth 
of  y%".  These  two  floats  are  separated  by 
two  bamboo  strips  as  shown  in  the  diagram, 


THE  COOK  NO.  42  MODEL  73 


CooJC  Kydro. 


Diagram  14 


74  MODEL  AEROPLANES 

which  are  tied  to  the  rounded  portion  of 
the  under  carriage  by  small  rubber  bands.  By 
the  sliding  of  these  strips  back  and  forth  the 
necessary  angle  of  the  floats  may  be  obtained  to 
suit  conditions.  The  floats  are  built  up  with 
two  thin  pieces  of  white  pine  for  sides,  sepa- 
rated by  small  pieces  of  wood  about  one-half 
the  size  of  a  match  in  cross  section.  Chiffon 
veiling  which  is  used  for  the  covering  of  the 
wings,  is  also  used  for  the  covering  of  the 
floats,  after  which  it  is  covered  with  a  special 
preparation  to  render  both  the  wings  and  the 
floats  air  and  water-tight. 

The  two  ten-inch  propellers  with  which  the 
model  is  fitted  have  a  theoretical  pitch  of  twelve 
and  one-half  inches.  The  propellers  are 
carved  from  blanks  one-half  inch  thick,  the 
blades  of  the  completed  propellers  having  a 
maximum  width  of  one  inch  at  a  radius  of 
three  inches.  The  propeller  shafts  are  made 
from  No.  16  piano  wire  and  have  small  wash- 
ers for  bearings.  Each  propeller  is  driven  by 
three  strands  of  %"  strip  elastic.  The  rub- 


THE  COOK  NO.  42  MODEL  75 

her  is  given  1700  to  1750  turns  and  revolves  the 
propellers  at  1150-1200  r.  p.  m.,  when  the 
model  is  in  flight. 

The  model  usually  runs  over  the  surface  of 
the  water  for  a  distance  of  from  two  to  three 
feet  before  it  rises,  after  which  it  climbs  at  a 
very  steep  angle  to  the  necessary  altitude. 
The  model  seems,  when  in  flight,  to  be  slightly 
overpowered  but  this  is  misleading.  The  rub- 
bers usually  unwind  in  from  85  to  90  seconds. 
On  four  out  of  six  flights  this  model  has  made 
a  duration  of  between  98  and  100  seconds 
which  is  rather  unusual  for  a  model  of  this 
type. 


THE  RUDY  FUNK  DURATION 
MODEL 

OF  the  many  different  types  of  duration 
models  that  have  made  their  appearance  dur- 
ing the  year  of  1915  perhaps  the  model  de- 
scribed herewith,  constructed  and  flown  by 
Mr.  Rudolph  Funk,  of  the  Aero  Science  Club, 
was  one  of  the  most  successful.  Unlike  most 
models  the  propellers  of  this  model  are  bent 
and  not  cut.  This  model  made  its  appearance 
during  the  latter  part  of  1915,  on  several  oc- 
casions having  flown  for  over  100  seconds  dur- 
ation. Diagram  15. 

While  retaining  the  important  characteristics 
of  his  standard  model,  slight  changes  have  been 
made.  Instead  of  the  usual  wire  for  the  con- 
struction of  the  frame  of  the  wings,  bamboo  is 
used  in  its  place  for  lightness  and  strength. 
The  wing  frames  are  single  surfaced,  China 

76 


RUDY  FUNK  MODEL  77 

silk  being  used  for  covering.  The  "dope" 
which  is  used  to  render  the  silk  airtight  is  made 
by  dissolving  celluloid  in  banana  oil.  This  in 
turn  is  applied  to  the  silk  with  a  soft  brush. 

The  camber  of  the  main  wing  is  24"  at 
the  center,  with  a  slight  reduction  towards 
the  negative  tips;  it  also  has  a  dihedral  angle 
of  2  degrees.  The  main  beam,  which  is  secured 
to  the  under  side  of  the  frame  for  rigidness,  is 
of  spruce  i"  by  5-64",  tapering  to  £4"  x  5-64". 
The  ribs  for  the  main  wing  and  small  wing  or 
"elevator"  are  cut  from  solid  pieces  of  bamboo 
3-16"  thick  by  J4"  wide.  These  pieces  of  bam- 
boo are  first  bent  to  the  proper  camber  and  are 
then  cut  into  strips  each  1-16"  wide.  The  ribs 
are  next  tapered  to  a  V  at  the  bottom,  toward 
the  trailing  edge,  as  shown  in  diagram  15,  and 
also  toward  the  entering  edge.  To  accommo- 
date the  entering  and  trailing  edges  of  the 
frame,  each  rib  is  slit  slightly  at  both  ends. 
Both  edges  of  the  frame  are  then  inserted  in  the 
slots  at  the  ends  of  the  ribs  and  bound  around 
with  silk  thread. 


MODEL  AEROPLANES 


Diagram  15 


RUDY  FUNK  MODEL  79 

The  frame  is  composed  of  two  sticks  of  silver 
spruce  38"  in  length,  5-16"  x  3-16",  tapering  to 
J4"  x  5-32",  held  apart  by  a  streamline  bamboo 
cross  brace  in  the  center.  An  additional  brace 
of  bamboo  is  securely  fastened  across  the  frame 
toward  the  front.  The  propeller  brace  con- 
sists of  a  streamline-cut  piece  of  bamboo  12^2 " 
in  length  by  y§"  in  width  at  the  center,  tapering 
to  y\"  toward  the  ends.  The  propeller  brace 
is  inserted  in  slots  cut  in  the  rear  ends  of  the 
frame  members,  then  bound  and  glued. 

The  propellers  are  bent  from  birch  veneer, 
the  bending  being  done  over  an  alcohol  flame 
as  illustrated  in  diagram  15.  But  first  of  all 
the  blades  are  cut  to  shape,  sandpapered  and 
finished  before  they  are  bent.  As  shown  in  the 
drawing  a  slot  is  filed  in  the  hub  of  each  blade 
to  enable  the  propeller  shaft  to  pass  through 
when  both  have  been  glued  together.  The 
blades  are  then  glued  and  bound  together,  first 
by  placing  a  piece  of  wire  in  the  slots  to  insure 
their  being  centered  and  also  to  prevent  their 
being  filled  with  glue.  After  this  has  been  done 


80  MODEL  AEROPLANES 

each  propeller  is  given  three  coats  of  the  same 
dope  as  is  used  on  the  wings. 

The  propeller  bearings  are  turned  out  of 
i  -32"  bronze  tubing,  the  length  of  each  bearing 
being  1/2".  Steel  washers  are  slipped  over 
the  propeller  shaft,  between  the  bearing  and 
propeller  to  insure  smooth  running.  The  pro- 
peller shafts  are  made  from  steel  hatpins  which 
are  heated  at  both  ends,  one  end  of  which  is 
bent  into  a  loop  to  receive  the  rubber  strands, 
the  other  end  being  bent  around  the  hub  of  the 
propeller  to  prevent  the  shaft  from  slipping 
during  the  unwinding  of  the  rubbers.  Two 
strips  of  brass,  each  J4"x  2",  are  bent  around 
the  one-half  inch  bearing  and  soldered.  The 
brass  strips  are  then  glued  and  bound  onto  the 
ends  of  the  propeller  brace  as  shown  in  diagram 


Rudy  Funk  speed  model 


Schober  compressed  air  driven  monoplane.     McMahon 
compressed  air  driven  tractor  (right) 


THE  ALSON  H.  WHEELER  WORLD 
RECORD  MODEL 

(TWIN    PUSHER    BIPLANE    143    SEC.    DURATION 
RISING   FROM   THE  GROUND) 

SINCE  the  beginning  of  model  flying  very 
little  attention  has  been  paid  to  the  model  bi- 
plane. Practically  all  records  are  held  by 
model  aeroplanes  of  the  monoplane  type. 
With  this  fact  in  view,  the  record  established 
by  Mr.  Wheeler  with  his  Twin  Pusher  Biplane 
is  extraordinary,  in  so  far  as  it  surpasses  many 
of  the  monoplane  records.  This  model  is  a 
very  slow  flyer,  and  has  excellent  gliding  abil- 
ity. At  the  time  when  this  model  flew  and 
broke  the  world's  record,  the  greater  portion  of 
the  flight  consisted  of  a  beautiful  glide  of  86 
seconds'  duration,  after  the  power  gave  out, 
making  it  possible  for  the  model  to  remain  in 
,  the  air  for  a  duration  of  143  seconds. 

81 


82  MODEL  AEROPLANES 

The  frame  consists  of  two  I-beams,  each 
48"  in  length,  running  parallel,  and  spaced  by 
cross  pieces,  each  piece  iij^"  long.  The 
bearing  blocks  used  made  it  possible  for  the 
propellers  to  clear  by  one-half  inch.  Two  12" 
expanding  pitch  racing  propellers  are  used 
and  these  are  mounted  on  ball  bearing  shafts. 
The  main  upper  plane  has  a  span  of  34"  with 
a  chord  of  5",  the  lower  plane  being  26"  by  5". 
The  elevator  consists  of  two  planes,  each  meas- 
uring 14"  by  5".  Cork  wheels  are  used,  each 
being  one  inch  in  diameter.  For  motive  power 
one-eighth  inch  flat  rubber  is  used,  this  being 
coated  with  glycerine  to  prevent  sticking. 


Alson  H.  Wheeler  twin  pusher  Biplane 


C  V.  Obst  tractor  model 


A  SIMPLE  COMPRESSED  AIR  MOTOR 

DURING  the  past  few  years  model  flyers  in 
America  have  shown  a  tendency  toward  the 
adoption  of  compressed  air  motors  for  use  in 
connection  with  model  aeroplanes.  Hitherto, 
England  has  been  the  home  of  the  compressed 
air  motor,  where  a  great  deal  of  experimenting 
has  been  carried  on,  to  a  considerable  degree 
of  success.  Flights  of  over  40  seconds  have 
been  made  with  models  in  which  compressed 
air  power  plants  were  used.  But,  however,  the 
desire  on  the  part  of  a  large  majority  of  model 
flyers  in  America  to  build  scientific  models,  that 
is,  models  more  closely  resembling  large  ma- 
chines, has  made  it  necessary  to  find  a  more 
suitable  means  of  propulsion;  rubber  strands 
being  unsatisfactory  for  such  purposes.  Many 
different  types  of  compressed  air  motors  have 
made  their  appearance  during  the  past  few 
years,  among  which  the  two  cylinder  opposed 

83 


84  MODEL  AEROPLANES 

type  is  very  favorably  looked  upon,  because  it 
is  perhaps  one  of  the  easiest  to  construct. 

To  make  a  simple  two  cylinder  opposed  com- 
pressed air  power  plant,  as  illustrated  in  Figure 
i  of  diagram  16,  it  is  not  necessary  that  the 
builder  be  in  possession  of  a  machine  shop.  A 
file,  drill,  small  gas  blow  torch  and  a  small  vise 
comprise  the  principal  tools  for  the  making  of 
the  motor. 

The  first  things  needed  in  the  making  of  this 
motor  are  cylinders.  For  the  making  of  the 
cylinders  two  fishing  rod  ferrules,  known  as 
female  ferrules,  are  required.  And  for  the 
heads  of  the  cylinders,  two  male  ferrules  are 
required.  Such  ferrules  can  be  secured  .at 
most  any  sporting  goods  store.  The  female 
ferrules  should  be  filed  down  to  a  length  of 
2",  cut  down  on  one  side  a  distance  of  y^ 
of  the  diameter,  then  cut  in  from  the  end  as 
shown  in  Figure  7.  When  this  has  been  done 
the  two  male  ferrules  should  be  cut  off  a  dis- 
tance of  %"  from  the  top  as  shown  in  Figure 
7a,  to  serve  as  heads  for  the  cylinders.  A  hole 


SIMPLE  COMPRESSED  AIR  MOTOR     85 


Flax,  fc&S  tf  /%o£or. 


Diagram  16 


86  MODEL  AEROPLANES 

y%"  in  diameter  should  be  drilled  in  the  center 
of  each  head  so  as  to  enable  the  connecting  of 
the  intake  pipes.  By  the  use  of  soft  wire  solder 
the  heads  should  be  soldered  into  the  ends  of  the 
cylinders  as  shown  in  Figure  id. 

The  pistons  should  now  be  made ;  for  this  pur- 
pose two  additional  male  ferrules  are  required. 
These  should  be  made  to  operate  freely  within 
the  cylinders  by  twisting  them  in  a  rag  which 
has  been  saturated  with  oil  and  upon  which  has 
been  shaken  fine  powdered  emery.  When  they 
have  been  made  to  operate  freely  they  should 
be  cut  down  one-half  inch  from  the  closed  end 
as  shown  in  Figure  5a.  For  the  connecting 
rods,  2  pieces  of  brass  tubing,  each  £&"  in 
diameter  by  ij4"  long,  are  required,  and,  as 
illustrated  in  Figure  6,  should  be  flattened  out 
at  either  end  and  through  each  end  a  hole  3-32" 
in  diameter  should  be  drilled.  For  the  con- 
necting of  the  piston  rods  to  the  pistons,  studs 
are  required,  and  these  should  be  cut  from  a 
piece  of  brass  rod  }4"  in  diameter  by  ^2" 
in  length.  As  two  studs  are  necessary,  one 


SIMPLE  COMPRESSED  AIR  MOTOR     87 

for  each  piston,  this  piece  should  be  cut  in 
half,  after  which  each  piece  should  be  filed  in 
at  one  end  deep  enough  to  receive  the  end  of 
the  connecting  rod.  Before  soldering  the 
studs  to  the  heads  of  the  pistons,  however, 
the  connecting  rods  should  be  joined  to  the 
studs  by  the  use  of  a  steel  pin  which  is  passed 
through  the  stud  and  connecting .  rod,  after 
which  the  ends  of  the  pin  are  flattened,  to  keep 
it  in  position  as  shown  in  Figure  5a. 

For  the  outside  valve  mechanism  and  also  to 
serve  in  the  capacity  as  a  bearing  for  the  crank- 
shaft, a  piece  of  brass  tubing  ^4"  in  diameter 
by  I1/*"  long  is  required.  Into  this  should  be 
drillpd  three  holes,  each  y%"  in  diameter,  and 
each  y*"  apart  as  shown  in  Figure  4.  Next, 
for  the  valve  shaft  and  also  propeller  accommo- 
dation, secure  a  piece  of  3-16"  drill  rod  2"  long. 
On  the  left  hand  side  of  the  valve  shaft,  as 
shown  in  Figure  3,  a  cut  1-32"  deep  by  J4"  in 
length  is  made  i"  from  the  end.  Another  cut 
of  the  same  dimensions  is  made  on  the  right 
side  only;  this  cut  is  made  at  a  distance  of  %" 
from  the  stud  end. 


88  MODEL  AEROPLANES 

As  shown  in  Figure  if,  the  crank  throw  con- 
sists of  a  flat  piece  of  steel,  3-32"  thick,  ^"  in 
length  by  J4"  in  width.  At  each  end  of  the 
crank  throw  a  hole  3-16"  in  diameter  should  be 
drilled,  the  holes  to  be  one-half  inch  apart. 
Into  one  hole  a  piece  of  steel  drill  rod  3-32"  in 
diameter  by  *4"  long  is  soldered,  to  which  the 
connecting  rods  are  mounted,  as  shown  in  Fig- 
ure i  f .  Into  the  other  hole  the  stud  end  of  the 
crank  throw  is  soldered. 

Before  making  the  tank  it  is  most  desirable 
to  assemble  the  parts  of  the  motor,  and  this 
may  be  done  by  first  fitting  the  pistons  into  the 
cylinders  as  shown  in  Figure  i-b,  after  which 
the  cylinders  should  be  lapped  one  over  the 
other  and  soldered  as  shown  in  Figure  i-a. 
When  this  has  been  done  a  hole  one-fourth  of 
an  inch  in  diameter  should  be  drilled  half  way 
between  the  ends  of  the  cylinders,  and  into 
this  hole  should  be  soldered  one  end  of  the  valve 
casing  shown  in  Figure  4.  For  the  inlet  pipes 
as  shown  in  Figure  i-c  secure  two  pieces  of 
y%"  brass  tubing  and  after  heating  until  soft, 


Schober  pusher  type  compressed  air  driven  monoplane 


«• 


Schober  compressed  air  driven  biplane 


SIMPLE  COMPRESSED  AIR  MOTOR     89 

bend  both  to  a  shape  similar  to  that  shown  in 
Figure  i-c.  When  this  has  been  done  solder 
one  end  to  the  end  of  the  cylinder  and  the  other 
in  the  second  hole  of  the  valve  shaft  casing. 
The  valve  shaft  should  now  be  inserted  in  the 
valve  shaft  casing  and  the  connecting  rods 
sprung  onto  the  crank  throw  as  shown  in  Fig- 
ure i-d.  To  loosen  up  the  parts  of  the  motor 
which  have  just  been  assembled  it  should  be 
filled  with  oil  and  by  tightly  holding  the  crank- 
shaft in  the  jaws  of  a  drill  the  motor  can  be 
worked  for  a  few  minutes. 

The  tank  is  made  from  a  sheet  of  brass  or 
copper  foil  15"  long  by  i-ioo"  thick.  This 
is  made  in  the  form  of  a  cylinder,  the  edges 
of  which  are  soldered  together  as  shown  in 
Figure  2*.  Sometimes  this  seam  is  riveted 
every  one-half  inch  to  increase  its  strength, 
but  in  most  cases  solder  is  all  that  is  required 
to  hold  the  edges  together.  For  the  caps,  or 
ends,  the  tops  of  two  small  oil  cans  are  used, 
each  can  measuring  2^/2"  in  diameter.  To 
complete  the  caps  two  discs  of  metal  should  be 


90  MODEL  AEROPLANES 

soldered  over  the  ends  of  the  cans  where  for- 
merly the  spouts  were  inserted,  the  bottoms  of 
the  cans  having  been  removed.  The  bottom 
edges  of  the  cans  should  be  soldered  to  the 
ends  of  the  tank  as  shown  in  Figure  2.  Into 
one  end  of  the  completed  tank  a  hole  large 
enough  to  receive  an  ordinary  bicycle  air  valve 
should  be  drilled.  Figure  2.  Another  hole  is 
drilled  into  the  other  end  of  the  tank,  into  which 
is  soldered  a  small  gas  cock  to  act  as  a  valve. 
Figure  2.  This  should  be  filed  down  where 
necessary,  to  eliminate  unnecessary  weight. 
To  connect  the  tank  with  the  motor,  a  piece  of 
]/%"  brass  tubing  3"  long  is  required,  the  ends 
of  which  are  soldered  into  the  holes  in  the  valve 
shaft  casing  nearest  the  cylinders,  as  shown  in 
Figure  i  ee.  As  shown  in  Figure  i  ee,  a  hole 
y%"  in  diameter  is  drilled  in  one  side  of  this 
piece,  but  not  through,  in  the  end  nearest  the 
tank.  Another  piece  of  brass  tubing  J^"  in 
diameter  is  required  to  connect  the  tank  with 
the  motor,  one  end  of  which  is  soldered  to  the 
cock  in  the  tank,  the  other  in  the  hole  in  the 


SIMPLE  COMPRESSED  AIR  MOTOR     91 

pipe  which  leads  from  the  motor  to  the  tank, 
illustrated  in  Figure  I  ee,  thus  completing  the 
motor. 

In  conclusion  it  is  suggested  that  the  builder 
exercise  careful  judgment  in  both  the  making 
and  assembling  of  the  different  parts  of  the 
motor  in  order  to  avoid  unnecessary  trouble 
and  secure  satisfactory  results.  After  having 
constructed  a  motor  as  has  just  been  described, 
the  constructor  may  find  it  to  his  desire  to  con- 
struct a  different  type  of  motor  for  experi- 
mental purposes.  The  constructor  therefore 
may  find  the  descriptions  of  satisfactory  com- 
pressed air  motors  in  the  following  paragraphs 
of  suggestive  value. 


COMPRESSED  AIR  MODELS 

THE    MC  MAHON   COMPRESSED  AIR   DRIVEN 
MONOPLANE 

ONE  of  the  latest  developments  in  the  field 
of  model  flying  is  the  McMahon  compressed  air 
driven  monoplane.  This  model  was  built  to 
be  used  as  either  a  tractor  or  pusher,  but  in  view 
of  its  ability  to  balance  more  easily  as  a  pusher 
most  of  the  experiments  have  been  carried  out 
on  this  machine  as  a  pusher.  The  machine  in 
itself  is  simple  and  inexpensive  to  construct,  the 
chief  portion  of  the  expense  being  involved  in 
the  making  of  the  motor.  By  using  the  ma- 
chine as  a  pusher  a  great  deal  of  protection  is 
afforded  both  the  propeller  and  motor,  and  this 
protection  helps  to  avoid  damaging  the  pro- 
peller or  motor,  which  would  mean  an  addi- 
tional expenditure  for  repairs,  thus  minimizing 

the  cost  of  flying  the  model. 

92 


COMPRESSED  AIR  MODELS          93 

The  frame  has  been  made  to  accommodate 
both  the  tank  and  motor,  and  this  is  done  by 
using  two  30"  strips  of  spruce,  each  J4"  wide 
by  y§"  deep,  laid  side  by  side,  a  distance  of 
three  inches  apart,  up  to  within  10"  of  the 
front,  as  shown  in  the  accompanying  photo- 
graph. No  braces  are  used  on  the  frame,  as 
the  tank,  when  securely  fastened  between  the 
frame,  acts  in  that  capacity. 

The  wings  are  made  in  two  sections,  each 
section  measuring  24"  in  span  by  8"  in  chord, 
consisting  of  two  main  spars,  3-16"  in  diameter, 
one  for  the  entering  edge  and  one  for  the  trail- 
ing edge.  To  these  edges,  at  a  distance  of 
three  inches  apart,  are  attached  bamboo  ribs, 
1 8  in  all,  each  measuring  8"  in  length  by  l/%" 
in  width  by  1-16"  thick.  The  wings  are  round 
at  the  tips,  and  have  a  camber  of  approximately 
one-half  inch,  but  they  are  not  set  at  an  angle 
of  incidence.  Light  China  silk  is  used  for 
covering  and  after  being  glued  over  the  top  of 
the  wing  frame  is  given  two  coats  of  dope  to 
shrink  and  fill  the  pores  of  the  fabric.  A  good 


94  MODEL  AEROPLANES 

"dope"  for  the  purpose  can  be  made  from  cel- 
luloid dissolved  in  banana  oil.  The  wing  sec- 
tions are  attached  to  the  frame  and  braced  by 
light  wire.  The  forward  wing  or  "elevator"  is 
made  in  the  same  manner  as  the  main  wing,  but 
should  measure  only  18"  x  3".  Instead  of  be- 
ing made  in  two  sections  as  the  main  wing,  the 
forward  wing  is  made  in  one  piece. 

The  chassis  is  made  by  forming  two  V  struts 
from  strong  steel  wire  sufficiently  large  enough 
so  that  when  they  are  attached  to  the  frame  of 
the  model  the  forward  part  will  be  9"  above  the 
ground.  One  V  strut  is  securely  fastened  to 
either  side  of  the  frame,  at  a  distance  of  8" 
from  the  front.  A  7"  axle  is  fastened  to  the 
ends  of  these  struts.  On  the  axle  are  mounted 
two  light  wheels,  each  about  2"  in  diameter. 
The  chassis  is  braced  by  light  piano  wire. 

The  rear  skid  is  made  in  the  same  manner  as 
the  forward  skid,  only  that  the  ends  of  the 
struts  are  brought  together  and  a  wheel  i  inch 
in  diameter  is  mounted  at  the  bottom  ends  by 
means  of  a  short  axle.  The  struts  are  not 


John  McMahon  and  his  compressed  air  driven 
monoplane 


Frank  Schober  preparing  his  model  for  flight. 
Gauge  to  determine  pressure  of  air  may  be 
seen  in  photograph 


COMPRESSED  AIR  MODELS  95 

more  than  7^"  long,  thus  allowing  a  slight 
angle  to  the  machine  when  it  is  resting  upon 
the  ground. 

The  machine  complete  does  not  weigh  over 
7  ounces.  The  power  plant  used  in  connection 
with  this  model  is  of  the  two  cylinder  opposed 
motor  type,  with  tank  such  as  has  just  been 
described  in  the  foregoing  chapter. 

The  tank  is  mounted  in  the  frame  by  drilling 
a  1-16"  hole  through  either  end  of  the  tank, 
through  which  a  drill  rod  of  this  diameter  can 
be  inserted.  About  %ths  of  the  drill  rod 
should  extend  out  on  each  side  of  the  tank,  to 
permit  the  fastening  of  the  tank  to  the  frame 
side  members.  This  method  of  mounting  the 
tank  serves  two  purposes  to  a  satisfactory  de- 
gree. First,  it  permits  secure  fastening;  sec- 
ond, as  the  rods  are  passed  through  the  side  and 
cap  of  the  tank  they  help  materially  in  prevent- 
ing the  caps  from  being  blown  off  in  the  event 
of  excessive  pressure. 


THE  MCMAHON  COMPRESSED  AIR  DRIVEN 
BIPLANE 

IN  the  McMahon  model  we  find  a  very  satis- 
factory type  of  compressed  air  driven  model. 
On  several  occasions  this  model  has  made 
flights  of  over  200  feet  with  a  duration  of  be- 
tween 10  and  15  secouds,  and  the  indications 
are  that  by  the  use  of  a  more  powerful  motor 
the  model  can  be  made  to  fly  a  greater  distance, 
with  a  corresponding  increase  of  duration. 
The  motor  used  in  connection  with  the  model 
is  of  the  two  cylinder  opposed  type,  such  as 
described  in  the  foregoing  paragraphs.  The 
tank,  however,  is  somewhat  different  in  design 
from  that  just  described,  it  having  been  made 
of  28  gauge  sheet  bronze,  riveted  every  one- 
half  inch.  The  two  long  bolts  that  hold  the 
steel  caps  on  either  end  of  the  tank  also  serve  as 
attachments  for  the  spars  that  hold  the  tank  to 
the  engine  bed,  as  shown  in  diagram  18.  The 
tank  has  been  satisfactorily  charged  to  a  pres- 

96 


COMPRESSED  AIR  MODELS  97 

sure  of  200  Ibs.  per  square  inch,  but  only  a  pres- 
sure of  150  Ibs.  is  necessary  to  operate  the 
motor.  The  tank  measures  10"  in  length  by 
3"  in  diameter  and  weighs  7  ounces. 

The  wings  of  this  machine  are  single  sur- 
faced and  covered  with  fiber  paper.  The  top 
wing  measures  42"  in  span  by  6"  in  chord. 
The  lower  wing  is  24"  by  6".  The  wings  have 
a  total  surface  of  396  square  inches  and  are 
built  up  of  two  3-16"  dowel  sticks,  flattened  to 
streamline  shape.  Only  two  sets  of  uprights 
separate  the  wings,  thus  adding  to  the  stream- 
line appearance  of  the  machine. 

Both  tail  and  rudder  are  double  surfaced  and 
are  built  entirely  of  bamboo  for  lightness, 
the  tail  being  made  in  the  form  of  a  half  cir- 
cle measuring  12"  by  8".  Steel  wire  is  used 
on  the  construction  of  the  landing  chassis,  the 
chassis  being  so  designed  as  to  render  it  capable 
of  withstanding  the  most  violent  shock  that  it 
may  possibly  receive  in  landing.  The  propeller 
used  in  connection  with  the  model  is  14"  in  di- 
ameter and  has  an  approximate  pitch  of  18". 


MODEL  AEROPLANES 


PI**.. 


/f^ 


\l 


fr 


Diagram  17 


COMPRESSED  AIR  MOTORS 

THE   WISE    COMPRESSED   AIR    MOTOR 

ALTHOUGH  of  peculiar  construction,  the 
Wise  rotary  compressed  air  motor  offers  a  very 
interesting  design  from  a  viewpoint  of  ingenu- 
ity. This  motor  embodies  a  number  of  novel 
features  not  hitherto  employed  in  the  construc- 
tion of  compressed  air  motors,  and  in  view  of 
the  fact  that  the  majority  of  compressed  air 
motors  are  made  on  the  principle  of  the  opposed 
type,  this  motor  suggests  many  possibilities  for 
the  rotary  type  motor. 

The  motor  consists  of  five  cylinders  and 
weighs  four  ounces,  including  the  propeller  and 
mounting  frame.  On  a  pressure  of  15  Ibs.  the 
motor  will  revolve  at  a  speed  of  1000  r.p.m. 
The  connecting  rods  are  fastened  to  the  crank- 
shaft by  means  of  segments  and  are  held  by 
two  rings,  making  it  possible  to  remove  any  one 

99 


ioo  MODEL  AEROPLANES 

piston  without  disturbing  the  others.  This  is 
done  by  simply  removing  a  nut  and  one  ring. 
The  crank  case  is  made  from  seamless  brass 
tubing,  into  which  the  cylinders  are  brazed. 
The  valve  cage  and  cylinder  heads  are  also 
turned  separately  and  brazed.  One  ring  only 
is  used  in  connection  with  the  pistons.  The 
cylinders  have  a  bore  of  11-32",  with  a  piston 
stroke  of  7-16".  In  view  of  the  fact  that  pull 
rods  show  a  greater  tendency  to  overcome  cen- 
trifugal force,  they  are  used  instead  of  push 
rods  to  operate  the  valves.  The  crankshaft  has 
but  one  post,  which  is  uncovered  in  turn  by  each 
inlet  pipe  as  the  motor  revolves.  The  "over- 
hang" method  is  used  to  mount  this  motor  to 
the  model.  With  the  exception  of  the  valve 
springs,  the  entire  motor,  including  the  mount- 
ing frame  and  tank,  is  made  of  brass. 

THE  SCHOBER-FUNK  COMPRESSED  AIR  MOTOR 

Two  of  the  most  enthusiastic  advocates  of 
the  compressed  air  motor  for  use  in  model  aero- 
planes are  Messrs.  Frank  Schober  and  Rudolph 


COMPRESSED 

Funk,  both  members  of  the  Aero  Science  Club. 
For  a  number  of  months  both  these  gentlemen 
have  experimented  with  compressed  air  motors 
of  various  designs,  until  they  finally  produced 
what  is  perhaps  one  of  the  most  satisfactory 
rotary  motors  now  in  use,  from  a  standpoint  of 
simplicity  and  results. 

As  can  be  seen  from  the  accompanying  illus- 
tration, this  little  engine  is  remarkably  simple 
in  appearance.  The  motor  complete,  with 
equipment,  weighs  at  the  most  but  14  ounces. 
The  cylinders,  three  in  all,  are  stamped  from 
brass  shells  for  strength  and  lightness.  The 
pistons  are  made  from  ebony  fiber.  The  cylin- 
ders have  a  bore  of  jH$",  with  a  piston  stroke 
of  y^".  The  crank  case  is  built  up  from 
a  small  piece  of  brass  tubing  and  is  drilled 
out  for  lightness.  The  crankshaft  is  hollow, 
and  is  supported  at  the  rear  by  a  special  bear- 
ing which  acts  as  a  rotary  valve,  admitting  the 
intake  through  the  crankshaft  and  permitting 
the  exhaust  to  escape  through  a  specially  con- 
structed bearing. 


"':i  MODEL  AEROPLANES 

The  tank  is  constructed  of  30  gauge  sheet 
bronze,  wire  wound,  and  fitted  at  the  ends  with 
spun  brass  caps.  The  actual  weight  of  the 
engine  alone  is  2^/2  ounces,  the  tank  and  fittings 
weighing  nl/2  ounces,  making  the  total  weight 
of  the  complete  power  plant  14  ounces. 

THE   SCHOBER    FOUR    CYLINDER   OPPOSED 
MOTOR 

Another  interesting  type  of  compressed  air 
motor  that  has  been  developed  in  America  is 
the  Schober  four  cylinder  opposed  motor. 
While  this  motor  is  different  in  appearance 
from  most  compressed  air  motors,  it  has  been 
made  to  work  satisfactorily  and  is  consistent 
with  the  same  high  class  construction  that  is 
displayed  in  most  all  of  Mr.  Schober's  motors. 
The  accompanying  diagram  17  illustrates  the 
method  of  operation  of  the  four  cylinder  motor. 

The  crank  case  is  constructed  from  four 
pieces  of  24  gauge  spring  brass,  substantially 
connected  in  the  form  of  a  rectangle,  the  top 
and  bottom  being  left  open.  The  front  and 


COMPRESSED,  AIR  MOTORS         103 


Diagram  18 


104  MODEL  AEROPLANES 

rear  walls  have  flanges  which  engage  the  inside 
of  the  side  walls  and  are  secured  thereto  by 
four  small  screws  on  each  side,  thereby  making 
it  an  easy  matter  to  take  the  crank  case  apart. 

"The  four  cylinders  are  made  from  drawn 
brass  shells  and  have  a  bore  of  y?'  and  stroke 
of  y2".  The  pistons  are  made  of  solid 
red  fiber.  The  two-throw  crank-shaft  is 
built  up  of  steel  with  brass  webs.  The 
bearings  are  of  steel.  The  valves,  being  over- 
head, are  driven  by  a  gear  mounted  at  the  end 
of  the  crankshaft,  the  gear  driving  the  valve 
shaft  by  means  of  a  gear  on  that  shaft,  with 
which  the  crankshaft  gear  meshes.  The  valve 
arrangement,  as  shown  in  diagram  18,  consists 
of  four  recesses  cut  into  the  valve  shaft,  two 
of  which  allow  the  air  to  pass  from  the  inlet 
pipes,  which  lead  into  the  valve  chamber  at  the 
center  of  same,  to  two  of  the  cylinders  at  once, 
while  the  other  two  recesses  allow  the  exhaust 
to  pass  from  openings  in  the  sides  of  the  valve 
chamber. 

The  cylinders  are  secured  to  the  side  plates 


The  interesting  horizontal-opposed  Jopson  gasoline  motor 
for  model  aeroplanes.  The  top  photograph  shows  the 
half-speed  shaft  and  the  arrangement  of  the  valve  mecha- 
nism. This  engine  is  air  cooled,  develops  I  h.p.  at  1,500 
r.p.m.,  and  weighs  7%  Ibs.,  including  gasoline  tank  and 
propeller.  The  bottom  view  shows  the  engine  with  pro- 
peller in  situ.  Courtesy  Flight. 


COMPRESSED  AIR  MOTORS         105 

of  the  crank  case  so  that  when  those  side  plates 
are  removed,  the  cylinders  are  removed  with 
them.  The  pipes  are  detachable  at  their  cen- 
ters; small  pipes  running  to  the  heads  of  the 
cylinders  extending  into  the  larger  pipes  which 
run  to  the  valve  chamber.  This  arrangement 
is  shown  in  the  end  view  of  the  engine.  A  17" 
propeller  is  used  in  connection  with  this  engine. 


GASOLINE  MOTORS 

THE   JOPSON    I    H.   P.   GASOLINE   MOTOR 
FOR   MODEL  AEROPLANES 

DURING  the  past  few  years  several  attempts 
have  been  made,  both  in  this  country  and 
abroad,  to  produce  a  reliable  gasoline  motor  for 
model  aeroplane  work,  but  mostly  without  any 
degree  of  success.  The  reason  for  this  inabil- 
ity, no  doubt,  is  due  to  the  scarcity  of  small 
working  parts  sufficiently  light  and  at  the  same 
time  reliable.  The  engine  described  herewith, 
designed  by  Mr.  W.  G.  Jopson,  a  member  of  the 
Manchester  Aero  Club,  England,  is  one  of  the 
few  that  have  been  made  to  work  satisfactorily. 

As  the  accompanying  diagrams  19  and  20 
and  photograph  show,  the  engine  is  of  the  four- 
cycle, horizontal  opposed  type,  having  two  cast- 
iron  cylinders  of  ij^"  bore  and  i%"  stroke. 
Each  cylinder  is  cast  in  one  piece,  and  as  the 

106 


Wise  five  cylinder  rotary  compressed  air  motor 


Schober-Funk  five  cylinder  rotary  motor 


GASOLINE  MOTORS  107 

engine  is  air  cooled,  they  are  cast  with  radiat- 
ing fins.  One  h.p.  is  developed  at  1500  r.p.m. 
The  total  weight  of  the  engine,  gasoline  tank 
and  propeller  is  *jy2  Ibs.  In  preparing  the  de- 
sign of  this  motor,  the  designs  of  similar  full- 
sized  aero  motors  were  followed  as  far  as  pos- 
sible. The  pistons  are  similar  to  those  used 
on  large  aeromotors  and  are  fitted  with  two 
rings ;  the  crankshaft  is  turned  out  of  two  inch 
special  bar  steel,  and  is  carried  in  two  phos- 
phor-bronze bearings.  There  is  no  special 
feature  about  the  connecting  rods,  these  being 
of  the  standard  type,  but  very  strong  and  light. 
To  enable  the  two  cylinders  to  be  exactly  op- 
posite one  another,  the  connecting-rods  are  off- 
set in  the  pistons  and  are  connected  to  the  lat- 
ter by  gudgeonpins.  The  aluminum  crank- 
case  is  extremely  simple,  being  cylindrical  and 
vertically  divided.  The  inlet  valves  are  auto- 
matic, the  exhaust  valves  being  mechanically 
operated;  the  cam-shaft  is  driven  from  the 
main  shaft  by  two-to-one  gearing.  To  assist 
the  exhaust,  and  also  the  cooling,  small  holes 


io8 


MODEL  AEROPLANES 


Diagram  19 

Sectional  elevation  of  the  I  h.p.  Jopson  gasoline  motor  for 
models.    The  disposition  of  the  gasoline  tank  and  wick 
carburettor  is  particularly  noteworthy.     It  will  be  seen 
that  metal   journals   are  provided   for  the   crank-shaft, 
which  is  turned  out  of  2-inch  bar  steel.    Courtesy  Flight. 


GASOLINE  MOTORS  109 

are  drilled  round  the  cylinder  in  such  a  position 
that  when  the  piston  is  at  the  inner  end  of  its 
stroke,  these  holes  are  uncovered,  thus  permit- 
ting the  hot  exhaust  to  escape,  and  so  relieve 
the  amount  passing  through  the  exhaust  valves. 
The  commutator  is  also  driven  off  the  cam- 
shaft, as  shown  in  the  drawing.  No  distribu- 
tor is  fitted  to  the  commutator,  as  small  ones 
are  somewhat  troublesome  and  very  light  coils 
are  obtainable  at  a  reasonable  price. 

The  gasoline  tank  is  made  of  copper  in 
stream-line  form,  and  is  usually  fitted  to  the 
back  of  the  crankcase,  thus  reducing  the  head 
resistance,  but  if  desired  it  can  be  fitted  in  any 
other  position.  The  action  of  the  carburettor 
can  be  easily  seen  from  the  drawings;  it  is  of 
the  surface  type  and  much  simpler,  lighter  and 
quite  as  efficient  as  the  spray  type.  Specially 
light  and  simple  spark  plugs  are  used,  that 
give  very  little  trouble.  The  propeller  used  in 
connection  with  this  motor  is  somewhat  out  of 
the  ordinary,  having  been  specially  designed 
for  this  engine,  and  patented.  The  propeller 


no  MODEL  AEROPLANES 

is  made  entirely  of  aluminum  and  has  a  varia- 
ble pitch,  this  being  easily  obtainable,  as  the 
blades  are  graduated  so  that  any  desired  pitch, 
within  certain  limits,  may  be  given  at  once. 
The  results  of  a  series  of  tests  on  a  30  inch  pro- 
peller are  shown  on  the  accompanying  chart, 
and  from  it  the  thrust  as  certain  speeds  with  a 
certain  pitch  can  be  obtained.  Taking  the  en- 
gine running  at  1540  r.p.m.  with  a  pitch  of  15", 
the  thrust  comes  out  at  9^2  Ibs.,  or  more  than 
the  weight  of  the  motor  and  accessories. 


GASOLINE  MOTORS 


X 


AT  1340  tPM, 


X 


X 


9  >Z  15 

PITCH  OF  BUAOE&CINCHES) 


Diagram  20 

Diagram  of  results  obtained  from  tests  of  the  I  h.p.  Jopson 
model  gasoline  motor,  showing  the  thrust  in  pounds  at 
varying  speeds  with  propellers  of  different  pitch.  Cour- 
tesy Flight 


THE  MIDGET  AERO  GASOLINE 
MOTOR 

ALTHOUGH  numerous  model  constructors  in 
America  are  experimenting  with  model  gaso- 
line motors,  the  Midget  Gasoline  Motor,  the 
product  of  the  Aero  Engine  Company,  Boston, 
Massachusetts,  is  perhaps  the  most  satisfac- 
tory up  to  the  present  time.  An  engine  of 
this  type  was  used  by  Mr.  P.  C.  McCutchen 
of  Philadelphia,  Pennsylvania,  in  his  8  foot 
Voisin  Type  Bi-plane  Model,  for  which  he 
claims  a  number  of  satisfactory  flights. 

The  motor  is  made  from  the  best  iron,  steel, 
aluminum  and  bronze  and  the  complete  weight 
including  a  special  carburettor,  spark  plug  and 
spark  coil  is  2,y2  Ibs.  From  the  top  of  the  cylin- 
der head  to  the  bottom  of  the  crank  case  the 
motor  measures  7".  It  is  possible  to  obtain 
from  this  motor  various  speeds  from  400  to 

112 


The  Midget  ^  H.  P.  gasoline  motor 


MIDGET  AERO  GASOLINE  MOTOR     113 

2700  r.p.m.,  at  which  speed  it  develops  J4  h.p. 
The  propeller  used  in  connection  with  this 
motor  measures  18"  in  diameter  and  has  a 
13"  pitch. 

It  might  be  of  interest  to  know  that  one  of 
the  parties  responsible  for  the  development  of 
this  motor  is  Mr.  H.  W.  Aitken,  a  former 
model  maker  and  who  is  now  connected  with 
one  of  the  largest  aeromotor  manufacturing 
companies  in  America. 


STEAM  POWER  PLANTS 

ASIDE  from  the  compressed  air  motor  there 
is  the  steam  driven  motor  which  has  been  used 
abroad  to  a  considerable  degree  of  success. 
Owing  to  the  difficulty  in  constructing  and 
operating  a  steam  driven  motor,  very  few 
model  flyers  in  America  have  devoted  any  at- 
tention to  the  development  of  this  motor  as  a 
means  of  propulsion  for  model  aeroplanes. 
But  irrespective  of  the  limitations  of  the  steam 
motor  a  great  deal  of  experimentation  has  been 
carried  on  in  England,  and  without  doubt  it  will 
soon  be  experimented  with  in  America.  Per- 
haps one  of  the  most  successful  steam  power 
plants  to  have  been  designed  since  the  develop- 
ment of  the  Langley  steam  driven  model,  is  the 
Groves  type  of  steam  power  plant,  designed  by 
Mr.  H.  H.  Groves,  of  England.  On  one  occa- 
sion several  flights  were  made  with  a  model 

114 


STEAM  POWER  PLANTS  115 

driven  by  a  small  steam  engine  of  the  Groves 
type  weighing  3  Ibs.  The  model  proved  itself 
capable  of  rising  from  the  ground  under  its 
own  power  and  when  launched  it  flew  a  distance 
of  450  feet.  This  is  not  a  long  flight  when 
compared  with  the  flight  made  by  Prof.  Lang- 
ley's  steam  driven  model  on  November  28, 
1896,  of  three-quarters  of  a  mile  in  I  minute 
and  45  seconds,  but  the  size  of  the  models  and 
also  that  Mr.  Groves'  model  only  made  a  dura- 
tion of  30  seconds,  must  be  considered.  The 
model  was  loaded  12  ounces  to  the  square  foot 
and  had  a  soaring  velocity  of  some  20  m.p.h. 
The  total  weight  of  the  power  plant  was  il/2 
Ibs.  Propeller  thrust  10  to  12  ounces.  The 
total  weight  of  the  model  was  48  ounces.  The 
type  of  steam  plant  used  in  connection  with  this 
model  was  of  the  flash  boiler,  pressure  fed  type, 
with  benzoline  for  fuel. 

Mr.  Groves  has  done  considerable  experi- 
menting with  the  steam  driven  type  power 
plant.  Many  of  the  designs  used  in  the  con- 
struction of  steam  plants  for  models  are  taken 


ii6  MODEL  AEROPLANES 

from  his  designs.  A  Groves  steam  power 
plant  is  employed  in  one  of  Mr.  V.  E.  Johnson's 
(Model  Editor  of  Flight)  model  hydroaero- 
planes, the  first  power-driven,  or  "mechanically 
driven"  model  hydroaeroplane  (so  far  as  can 
be  learned)  to  rise  from  the  surface  of  the 
water  under  its  own  power.  This  model  has  a 
total  weight  of  3  Ibs.  4  ounces. 

Another  advocate  of  the  steam  driven  type 
model  is  Mr.  G.  Harris,  also  of  England.  Sev- 
eral good  flights  were  made  by  Mr.  Harris 
with  his  pusher  type  monoplane  equipped  with 
a  steam  driven  motor.  As  a  result  of  his  ex- 
periments he  concluded  that  mushroom  valves 
with  a  lift  of  1-64  part  of  an  inch  were  best, 
used  in  connection  with  the  pump,  and  at  least 
12  feet  of  steel  tubing  should  be  used  for  boiler 
coils.  The  first  power  plant  constructed  by 
Mr.  Harris  contained  a  boiler  coil  8  feet  long, 
but  after  he  had  replaced  this  coil  with  one  12 
feet  long,  irrespective  of  the  fact  that  the  extra 
length  of  tube  weighed  a  couple  of  ounces,  the 
thrust  was  increased  by  nearly  a  half  pound. 


An  English  steam  power  plant  for  model  aeroplanes. 
Courtesy  Flight. 


Model  hydroaeroplane  owned  by  V.  E.  Johnson,  Model  Edi- 
tor of  Flight,  England,  equipped  with  an  H.  H.  Groves 
steam  power  plant.  This  model  is  the  first  power  driven— 
as  far  as  can  be  learned— to  rise  from  the  surface  of  the 

water  under  its  own  power.     Courtesy  Flight. 


STEAM  POWER  PLANTS  117 

The  principal  parts  used  in  Mr.  Harris's  steam 
power  plant  was  an  engine  of  the  H.  H.  Groves 
type,  twin  cylinder,  %"  bore  with  a  piston 
stroke  of  y2".  The  boiler  was  made  from  12" 
of  3-16"  x  20"  G.  steel  tubing,  weighing  10.5 
ounces.  The  blow  lamp  consisted  of  a  steel 
tube,  5-32"  x  22"  G.  wound  round  a  carbide 
carrier  for  a  nozzle.  The  tank  was  made 
of  brass  5-1000"  thick.  The  pump,  7-32"  bore, 
stroke  variable  to  J4",  fitted  with  two  non-re- 
turn valves  (mushroom  type)  and  was  geared 
down  from  the  engine  4.5  to  I. 

The  Langley  steam  driven  model,  of  which 
so  much  has  been  said,  and  which  on  one  occa- 
sion flew  a  distance  of  one-half  mile  in  90  sec- 
onds, had  a  total  weight  of  30  Ibs.,  the  motor 
and  generating  plant  constituting  one-quarter 
of  this  weight.  The  weight  of  the  complete 
plant  worked  out  to  7  Ibs.  per  h.p.  The  engine 
developed  from  i  to  1^2  h.p.  A  flash  type 
boiler  was  used,  with  a  steam  pressure  of  from 
150  to  200  Ibs.,  the  coils  having  been  made  of 
copper.  A  modified  naphtha  blow-torch,  such 


ii8  MODEL  AEROPLANES 

as  is  used  by  plumbers,  was  used  to  eject  a  blast 
or  flame  about  2000  Fahrenheit  through  the 
center  of  this  coil.  A  pump  was  used  for  cir- 
culation purposes.  With  the  best  mechanical 
assistance  that  could  be  obtained  at  that  date, 
it  took  Professor  Langley  one  year  to  construct 
the  model. 

About  ten  months  after  Langley's  results, 
some  experiments  were  carried  out  by  the 
French  at  Carquenez,  near  Toulon.  The 
model  used  for  the  experiments  weighed  in 
total  70  Ibs.,  the  engine  developing  more  than 
I  h.p.  As  in  the  Langley  case,  twin  propellers 
were  used,  but  instead  of  being  mounted  side  by 
side,  they  were  mounted  one  in  front  and  the 
other  behind.  The  result  of  these  experiments 
compared  very  poorly  with  Langley's.  A 
flight  of  only  462  feet  was  made,  with  a  dura- 
tion of  a  few  seconds.  The  maximum  velocity 
is  stated  to  have  been  40  m.p.h.  The  span  of 
this  model  was  a  little  more  than  6  meters,  or 
about  19  feet,  with  a  surface  of  more  than  8 
square  meters,  or  about  80  square  feet. 


An  English  hydroaeroplane  of  tractor  design  equipped  with 
steam  power  plant.     Courtesy  Flight. 


On  the  right  an  English  10  oz.  Compressed  air  driven  bi- 
plane On  the  left,  the  engine  shown  fitted  with  a  simple 
speedometer  for  experimental  purposes.  Courtesy  Flight. 


WORLD'S  MODEL  FLYING  RECORDS 
(TwiN  PROPELLER  PUSHER  TYPE  MODELS) 

MONOPLANE 

Year  1916.  Thomas  Hall  (America),  hand  launched, 
distance  5337  feet. 

Year  1915.  Wallace  A.  Lauder  (America),  hand 
launched,  distance  3537  feet. 

Year  1915.  Wallace  A.  Lauder  (America),  hand 
launched,  duration  195  seconds. 

Year  1914.  Fred  Watkins  (America),  rise  off  ground, 
distance  1761  feet. 

Year  1914.  J.  E.  Louch  (England),  rise  off  ground, 
duration  169  seconds. 

Year  1915:  E.  C.  Cook  (America),  rise  off  water,  dur- 
ation 100  seconds. 

(TwiN  PROPELLER  TRACTOR  TYPE) 

MONOPLANE 

Year  1913.  Harry  Herzog  (America),  rise  off  water, 
duration  28  seconds. 

(TwiN  PROPELLER  PUSHER  TYPE) 
BIPLANE 

Year    1915.     A.    H.    Wheeler    (America),    rise    off 
ground,  duration  143  seconds. 
119 


120  MODEL  AEROPLANES 

(SINGLE  PROPELLER  PUSHER  TYPE) 

MONOPLANE 

Year  1914.     J.  E.  Louch  (England),  hand  launched, 

duration  95  seconds. 
Year  1914.    W.  E.  Evans  (England),  rise  from  ground, 

distance  870  feet. 
Year  1914.    J.  E.  Louch  (England),  rise  from  ground, 

duration  68  seconds. 
Year  1914.     L.  H.  Slatter  (England),  rise  from  water, 

duration  35  seconds. 

(SINGLE  PROPELLER  TRACTOR  TYPE) 
MONOPLANE 

Year  1915.     D.  Lathrop   (America),  hand  launched, 

distance  1039  feet. 
Year  1915.     D.  Lathrop   (America),  hand  launched, 

duration  240  seconds. 
Year    1914.     C    D.    Button    (England),    rise    from 

ground,  distance  570  feet. 
Year  1914.    J.  E.  Louch  (England),  rise  from  ground, 

duration  94  seconds. 
Year  1915.     L.  Kittle   (America),  rise  from  water, 

duration  116  seconds. 

(SINGLE  PROPELLER  TRACTOR  TYPE) 

BIPLANE 

Year  1915.     Laird  Hall  (America),  rise  from  ground, 
duration  76  seconds. 


FLYING  RECORDS  121 

(FLYING  BOAT  TYPE) 
MONOPLANE 

Year  1915.    Robert  La  Tour  (America),  rise  from 
water,  duration  43  seconds. 

(FLYING  BOAT  TYPE) 

BIPLANE 

Year  1914.    C.  V.  Obst  (America),  rise  from  water, 
duration  27  seconds. 

(MECHANICAL  DRIVEN  MODEL) 

Year  1914.     D.  Stanger  (England),  rise  from  ground, 
duration  51  seconds. 
(All  British  records  are  quoted  from  Flight) 


DICTIONARY  OF  AERONAUTICAL 
TERMS 


AERODROME — A  tract  of  land  selected  for  flying  pur- 
poses. 

AERODYNAMICS — The  science  of  Aviation,  literally  the 
study  of  the  influence  of  air  in  motion. 

AEROFOIL — A  flat  or  flexed  plane  which  lends  support 
to  an  aeroplane. 

AERONAUT — One  engaged  in  navigating  the  air. 

AERONAUTICS — The  science  of  navigating  the  air. 

AEROPLANE — A  heavier  than  air  machine  supported  by 
one  or  more  fixed  wings  or  planes. 

AEROSTATICS — The  science  of  aerostation,  or  of  buoy- 
ancy caused  by  displacement,  ballooning. 

AEROSTATION — The  science  of  lighter  than  air  or  gas- 
born  machines. 

AILERON — The  outer  edge  or  tip  of  a  wing,  usually 
adjustable,  used  to  balance  or  stabilize. 

AIRSHIP — Commonly  used  to  denote  both  heavier  and 
lighter  than  air  machines;  correctly  a  dirigible 
balloon. 

ANGLE  OF  INCIDENCE — The  angle  of  the  wing  with 
the  line  of  travel. 

122 


DICTIONARY  OF  TERMS  123 

ARES — In  the  case  of  wings,  the  extent  of  surface 
measured  on  both  the  upper  and  lower  sides.  An 
area  of  one  square  foot  comprises  the  actual  sur- 
face of  two  square  feet. 

ASPECT  RATIO — The  proportion  of  the  chord  to  the 
span  of  a  wing.  For  example  if  the  wing  has  a 
span  of  30  inches  and  a  chord  of  6  inches  the 

span 

aspect  ratio  will  be  5  or  —. — , 

Chord. 

AUTOMATIC  STABILITY — Stability  secured  by  fins,  the 
angle  of  tne  wings  and  similar  devices. 

AVIATOR — One  engaged  in  Aviation. 

AVIATION — The  science  of  heavier  than  air  machines. 

ANGLE  OF  BLADE — The  angle  of  the  blade  of  a  propeller 
to  the  axis  of  the  shaft. 


B 

BALANCER — A  plane  or  other  part  intended  for  lateral 

equilibrium. 

BEARING  BLOCK — Used  in  connection  with  the  mount- 
ing  of   propellers   on   model   aeroplanes.     Made 

from  wood  and  metal. 
BRACE — Strip  of  bamboo  or  other  material  used  to  join 

together  the  frame  side  members.     Also  used  in 

joining  other  parts  of  a  model. 
BIPLANE — An  aeroplane  or  model  aeroplane  with  two 

wings  superposed. 
BODY — The  main  framework  supporting  the  wing  or 

wings  and  the  machinery. 


i24  MODEL  AEROPLANES 

BANKING — The  lateral  tilting  of  an  aeroplane  when 
taking  a  turn. 

C 

CAMBER — The  rise  of  the  curved  contour  of  an  arched 
surface  above  the  Chord  Line. 

CENTER  OF  GRAVITY — The  point  at  which  the  aero- 
plane balances. 

CENTER  OF  PRESSURE — The  imaginary  line  beneath  the 
wing  at  which  the  pressure  balances. 

CHASSIS  (CARRIAGE) — The  part  on  which  the  main 
body  of  an  aeroplane  or  model  aeroplane  is  sup- 
ported on  land  or  water. 

CHORD — The  distance  between  the  entering  and  trail- 
ing edges  of  a  wing. 

D 

DECK — The  main  surface  of  a  biplane  or  multiplane. 
DIRECTIONAL  CONTROL — The  ability  to  determine  the 

direction  of  the  flight  of  an  aeroplane. 
DIRIGIBLE — A  balloon  driven  by  power. 
DOPE — A  coating  for  wings. 
DOWN  WING — With  the  wind. 
DRIFT — The  resistance  of  the  wing  to  the  forward 

movement. 
DIHEDRAL  ANGLE — The  inclination  of  the  wings  to  each 

other  usually  bent  up  from  the  center  in  the  form 

of  a  flat  V. 

E 

ELEVATOR — The  plane  or  wing  intended  to  control  the 
vertical  flight  of  the  machine. 


DICTIONARY  OF  TERMS  125 

ENGINEER — One  who  controls  the  power,  driving  the 

machinery. 
ENTERING  EDGE  or  LEADING  EDGE — Front  edge  or  edge 

of  the  surface  upon  which  the  air  impinges. 
EQUILIBRATOR — A  plane  or  other  contrivance  which 

makes  for  stability. 


FIN — A  fixed  vertical  plane. 

FLEXED — A  wing  is  said  to  be  flexed  when  it  curves  up- 
ward forming  an  arc  of  a  circle. 

FLYING  STICK — Name  applied  to  ordinary  A  type  and 
single  stick  models. 

FLYING  MACHINE — Literally  a  form  of  lighter  than 
air  craft ;  a  gas-borne  airship. 

FLYING  BOAT — A  hull  or  large  float  used  in  connection 
with  an  aeroplane  to  enable  its  rising  from  and 
alighting  upon  the  surface  of  the  water. 

FRAME — A  single  or  double  stick  structure  to  which  all 
parts  of  a  model  are  attached.  Three  or  more 
sticks  are  sometimes  employed  in  the  construction 
of  a  frame.  However,  the  usual  number  is  two, 
joined  together  in  the  form  of  letter  "A." 

FRAME  HOOKS — The  looped  ends  of  a  piece  of  wire  at- 
tached to  the  point  of  the  frame  to  accommodate 
the  S  hooks  attached  to  the  rubber  strands. 

FRAME  SIDE  MEMBERS — Two  main  sticks  of  an  A  type 
frame. 

FUSELAGE — The  body  or  framework  of  an  aeroplane. 


126  MODEL  AEROPLANES 


GLIDER — An  aeroplane  without  motive  power. 

GUY — A  brace,  usually  a  wire  or  cord  used  for  tuning 
up  the  aeroplane. 

GROSS  WEIGHT — The  weight  of  the  aircraft,  compris- 
ing fuel,  lubricating  oils  and  the  pilot. 

GYROSCOPE — A  rotating  mechanism  for  maintaining 
equilibrium. 

GAP — The  vertical  distance  between  the  superposed 
wings. 

H 

HANGAR — A  shed  for  housing  an  aeroplane. 

HARBOR — A  shelter  for  aircraft. 

HEAVIER  THAN  AIR — A  machine  weighing  more  than 
the  air  it  displaces. 

HELLI COPTER — A  flying  machine  in  which  propellers  are 
utilized  to  give  a  lifting  effect  by  their  own  direct 
action  on  the  air.  In  aviation  the  term  implies 
that  the  screw  exerts  a  direct  lift. 

HELMSMAN — One  in  charge  of  the  steering  device. 

HYDROAEROPLANE — An  aeroplane  with  pontoons  to  en- 
able its  rising  from  the  surface  of  the  water. 
Known  as  hydro  in  model  circles. 

K 

KEEL — A  vertical  plane  or  planes  arranged  longitudi- 
nally either  above  or  below  the  body  for  the  pur- 
pose of  giving  stability. 


DICTIONARY  OF  TERMS  127 

L 

LATERAL  STABILITY — Stability  which  prevents  side  mo- 
tion. 

LOADING — The  gross  weight  divided  by  the  supporting 
area  measured  in  square  feet. 

LONGITUDINAL  STABILITY — Stability  which  prevents 
fore  and  aft  motion  or  pitching. 

LONGERONS — Main  members  of  the  fuselage.  Some- 
times called  longitudinals. 

M 

MAST — A  perpendicular  stick  holding  the  stays  or 
struts  which  keep  the  wings  rigid. 

MODEL  AEROPLANE — A  scale  reproduction  of  a  man- 
carrying  machine. 

MECHANICAL  POWER — A  model  driven  by  means  other 
than  rubber  strands  such  as  compressed  air,  steam, 
gasoline,  spring,  electricity  and  so  forth  is  termed 
a  mechanical  driven  model.  The  power  used  is 
termed  mechanical  power. 

MOTIVE  POWER — In  connection  with  model  aeroplanes  a 
number  of  rubber  strands  evenly  strung  from  the 
propeller  shaft  to  the  frame  hooks  which  while 
unwinding  furnish  the  necessary  power  to  propel 
the  model. 

MAIN  BEAM — In  connection  with  model  aeroplanes 
a  long  stick  which  is  secured  to  the  under  side  of 
the  wing  frame  at  the  highest  point  in  the  curve 
of  the  ribs  adding  materially  to  the  rigidity  of  the 
wing. 


128  MODEL  AEROPLANES 

MONOPLANE — An  aeroplane  or  heavier  than  air  ma- 
chine supported  by  a  single  main  wing  which  may 
be  formed  of  two  wings  extending  from  a  central 
body. 

MOTOR — A  contrivance  for  generating  driving  power. 

MULTIPLANE— An  aeroplane  with  more  than  four 
wings  superposed. 

MOTOR  BASE — Main  stick  used  for  frame  of  single  stick 
model. 

N 

NACELLE — The  car  of  a  dirigible  balloon,  literally  a 
cradle.  Also  applied  to  short  body  used  in  connec- 
tion with  aeroplanes  for  the  accommodation  of  the 
pilot  and  motor. 

NET  WEIGHT — Complete  weight  of  the  machine  with- 
out pilot,  fuel  or  oil. 


ORNITHOPTER — A  flapping  wing  machine  which  has 
arched  wings  like  those  of  a  bird. 

ORTHOGONAL — A  flight  maintained  by  flapping  wings. 

OUTRIGGERS — Members  which  extend  forward  or  rear- 
ward from  the  main  planes  for  the  purpose  of 
supporting  the  elevator  or  tail  planes  of  an  aero- 
plane. 

P 

PLANE — A  surface  or  wing,  either  plain  or  flexed,  em- 
ployed to  support  or  control  an  aeroplane. 
PILOT — One  directing  an  aeroplane  in  flight. 


DICTIONARY  OF  TERMS  129 

PITCH — Theoretical  distance  covered  by  a  propeller  in 

making  one  revolution. 

PROPELLER — The  screw  used  for  driving  an  aeroplane. 
PROPELLER  BEARINGS — Pieces  of  bronze  tubing  or  strips 

of  metal  formed  to  the  shape  of  the  letter  "L" 

used  to  mount  propellers.    Also  made  from  blocks 

of  wood. 
PROPELLER  BLANK — A  block  of  wood  cut  to  the  design 

of  a  propeller. 
PROPELLER  SPAR(S) — The  heavy  stick  or  sticks  upon 

which  the  bearing  or  bearings  of  a  single  or  twin 

propeller  model  are  mounted. 
PROPELLER  SHAFT — A  piece  of  wire  which  is  run 

through  the  hub  of  the  propeller  and  tubing  in 

mounting  the  propeller. 
PYLON — Correctly,  a  structure  housing  a  falling  weight 

used  for  starting  an  aeroplane,  commonly  a  turn- 
ing point  in  aeroplane  flights. 
PUSHER — An  aeroplane  with  the  propeller  or  propellers 

situated  in  back  of  the  main  supporting  surfaces. 


QUADRUPLANE — An  aeroplane  with  four  wings  super- 
posed. 


RUDDER — A  plane  or  group  of  planes  used  to  steer  an 

aeroplane. 
RUNNER — Strip  beneath  an  aeroplane  used  for  a  skid. 


130  MODEL  AEROPLANES 

RUNNING  GEAR  or  LANDING  GEAR — That  portion  of 
the  chassis  consisting  of  the  axle,  wheels  and  shock 
absorber. 

RIB — Curved  brace  fastened  to  the  entering  and  trail- 
ing edges  of  a  wing. 


SCALE  MODEL — A  miniature  aeroplane  exactly  repro- 
ducing the  proportions  of  an  original. 

SPAR — A  mast  strut  or  brace. 

SIDE  SLIP — The  tendency  of  an  aeroplane  to  slide  or 
slip  sideways  when  too  steep  banking  is  attempted. 

STABILITY — The  power  to  maintain  an  even  keel  in 
flight. 

STARTING  PLATFORM — A  runway  to  enable  an  aero- 
plane to  leave  the  ground. 

SURFACE  FRICTION — Resistance  offered  by  planes  or 
wings. 

SLIP — The  difference  between  the  distance  actually 
traveled  by  a  propeller  and  that  measured  by  the 
pitch. 

SOARING  FLIGHT — A  gliding  movement  without  ap- 
parent effort. 

SUSTAINING  SURFACE — Extent  of  the  wings  or  planes 
which  lend  support  to  an  aeroplane. 

SPAN  (SPREAD) — The  dimension  of  a  surface  across 
the  air  stream. 

STREAMLINE — Exposing  as  little  surface  as  possible  to 
offer  resistance  to  air. 


DICTIONARY  OF  TERMS  131 

SKIDS — In  connection  with  model  aeroplanes,  steel 
wires  or  strips  of  bamboo  allowed  to  extend  below 
the  frame  to  protect  the  model  in  landing  and  to 
permit  its  rising  off  the  ground  or  ice. 

S  OR  MOTOR  HOOKS — A  piece  of  wire  bent  in  a  double 
hook  to  resemble  the  letter  "S."  One  end  to 
be  attached  to  the  frame  hook,  the  other  serving 
as  accommodation  for  the  rubber  strands. 


TAIL — The  plane  or  planes,  both  horizontal  and  verti- 
cal, carried  behind  the  main  planes. 

TANDEM — An  arrangement  of  two  planes  one  behind 
the  other. 

THRUST — The  power  exerted  by  the  propeller  of  an 
aeroplane. 

TENSION — The  power  exerted  by  twisted  strands  of 
rubber  in  unwinding. 

TRACTOR — An  aeroplane  with  the  propeller  situated  be- 
fore the  main  supporting  surfaces. 

TRIPLANE — An  aeroplane  with  three  wings  superposed. 

TRAILING  EDGE — The  rear  edge  of  a  surface. 

TORQUE — The  twisting  force  of  a  propeller  tending  to 
overturn  or  swerve  an  aeroplane  sideways. 

U 
UP  WIND — Against  the  wind. 

W 

WAKE — The  churned  or  disturbed  air  in  the  track  of  a 
moving  aeroplane. 


132  MODEL  AEROPLANES 

WASH — The  movement  of  the  air  radiating  from  the 
sides  of  an  aeroplane  in  flight. 

WINGS — Planes  or  supporting  surfaces,  commonly  a 
pair  of  wings  extending  out  from  a  central  body. 

WINDER — An  apparatus  used  for  winding  two  sets  of 
rubber  strands  at  the  same  time  in  opposite  direc- 
tions or  one  at  a  time.  Very  often  made  from  an 
egg  beater  or  hand  drill. 

WARPING — The  springing  of  a  wing  out  of  its  normal 
shape,  thereby  creating  a  temporary  difference  in 
the  extremities  of  the  wing  which  enables  the  wind 
to  heel  the  machine  back  again  into  balance. 

ABREVIATIONS 

H.  P.    Horse  Power. 

R.  P.  M.  Revolutions  per  minute. 

H.  L.     Hand  launched. 

R.  O.  G.    Rise  off  ground  model. 

R.  O.  W.    Rise  off  water  model. 

M.  P.  H.    Miles  per  hour. 


THE   END 


14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

LOAN  DEPT. 

This  book  is  due  on  the  last  date  stamped  below, 
or  on  the  date  to  which  renewed.  Renewals  only: 

Tel.  No.  642-3405 

Renewals  may  be  made  4  days  prior  to  date  due. 
Renewed  books  are  subject  to  immediate  recall. 


29  197361 


General  Library 
Univershy^ California 


